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  <TITLE>S-8</TITLE>
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   <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>As filed with the Securities and Exchange Commission on March&nbsp;20, 2025 </B></P>
  <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="right"><B>Registration No.&nbsp;333-&#8195;&#8195;&#8195; </B></P> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
  <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P>
  <P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>UNITED STATES </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>SECURITIES
  AND EXCHANGE COMMISSION </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Washington, D.C. 20549 </B></P>
  <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
  <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>FORM <FONT STYLE="white-space:nowrap">S-8</FONT> </B></P>
  <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>REGISTRATION STATEMENT </B></P>
  <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B><I>UNDER </I></B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B><I>THE
  SECURITIES ACT OF 1933 </I></B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
  <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:24pt; font-family:Times New Roman" ALIGN="center"><B>Tectonic Therapeutic, Inc. </B></P>
  <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(Exact name of registrant as specified in its charter) </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
  <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
  <TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">
  
  
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  <TD VALIGN="top" ALIGN="center"><B>Delaware</B></TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="top" ALIGN="center"><B><FONT STYLE="white-space:nowrap">83-0710585</FONT></B></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
  <TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(State or other jurisdiction of</B></P>
  <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>incorporation or organization)</B></P></TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(I.R.S. Employer</B></P>
  <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Identification No.)</B></P></TD></TR>
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  <TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>490 Arsenal Way</B></P>
  <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Suite 210</B></P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Watertown,
  MA</B></P></TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="bottom" ALIGN="center"><B>02472</B></TD></TR>
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  <TD VALIGN="top" ALIGN="center"><B>(Address of Principal Executive Offices)</B></TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="top" ALIGN="center"><B>(Zip Code)</B></TD></TR>
  </TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>2024 Equity Incentive Plan </B></P>
  <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>2024 Employee Stock Purchase Plan </B></P>
  <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Full titles of the plans) </B></P>
  <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Daniel Lochner </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Chief
  Financial Officer </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>490 Arsenal Way </B></P>
  <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Suite 210 </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Watertown, MA
  02472 </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(339) <FONT STYLE="white-space:nowrap">666-3320</FONT> </B></P>
  <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Name, address, including zip code, and telephone number, including area code, of agent for service) </B></P>
  <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
  <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B><I>Copies to: </I></B></P>
  <P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Divakar S. Gupta </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Brandon
  Fenn </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Minkyu Park </B></P>
  <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Cooley LLP </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>55 Hudson
  Yards </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>New York, New York 10001 </B></P>
  <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(212) <FONT STYLE="white-space:nowrap">479-6000</FONT> </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
  <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Indicate by
  check mark whether the registrant is a large accelerated filer, an accelerated filer, a <FONT STYLE="white-space:nowrap">non-accelerated</FONT> filer, a smaller reporting company or an emerging growth company. See the definitions of &#147;large
  accelerated filer,&#148; &#147;accelerated filer,&#148; &#147;smaller reporting company,&#148; and &#147;emerging growth company&#148; in Rule <FONT STYLE="white-space:nowrap">12b-2</FONT> of the Exchange Act. </P>
  <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
  <TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">
  
  
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  <TD VALIGN="bottom">Large&nbsp;accelerated&nbsp;filer</TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="bottom">&#9744;</TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="bottom">Accelerated Filer</TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="bottom">&#9744;</TD></TR>
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  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="bottom"><FONT STYLE="white-space:nowrap">Non-accelerated&nbsp;filer</FONT></TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="bottom">&#9746;</TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="bottom">Smaller&nbsp;reporting&nbsp;company</TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="bottom">&#9746;</TD></TR>
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  <TD VALIGN="bottom">&nbsp;</TD>
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  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="bottom">Emerging growth company</TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="bottom">&#9744;</TD></TR>
  </TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended
  transition period for complying with any new or revised financial accounting standards provided pursuant to Section&nbsp;7(a)(2)(B) of the Securities Act.&#8194;&#9744; </P> <P STYLE="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
  <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P>
  </DIV></Center>
  
  
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   <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>REGISTRATION OF ADDITIONAL SHARES PURSUANT TO GENERAL INSTRUCTION E </B></P>
  <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Tectonic Therapeutic, Inc. (the &#147;Registrant&#148;) is filing this Registration Statement on Form
  <FONT STYLE="white-space:nowrap">S-8</FONT> with the Securities and Exchange commission (the &#147;<B><I>Commission</I></B>&#148;) for the purpose of registering (a) 742,815 shares of the Registrant&#146;s common stock, par value $0.0001 (the
  &#147;<B><I>Common Stock</I></B>&#148;), issuable to eligible persons under the Registrant&#146;s 2024 Equity Incentive Plan (the &#147;<B><I>2024 Plan</I></B>&#148;), pursuant to the provisions of the 2024 Plan providing for an automatic increase
  in the number of shares of Common Stock reserved and available for issuance under the 2024 Plan on January&nbsp;1, 2025 and (b) 148,563 shares of Common Stock issuable to eligible persons under the Registrant&#146;s 2024 Employee Stock Purchase Plan
  (the &#147;<B><I>2024 ESPP</I></B>&#148;), pursuant to the provisions of the 2024 ESPP providing for an automatic increase in the number of shares of Common Stock reserved and available for issuance under the 2024 ESPP on January&nbsp;1, 2025. In
  accordance with the instructional note to Part I of Form <FONT STYLE="white-space:nowrap">S-8</FONT> as promulgated by the Commission, the information specified by Part I of the Form <FONT STYLE="white-space:nowrap">S-8</FONT> has been omitted from
  this Registration Statement. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">These shares of Common Stock are additional securities of the same class as other securities for which the
  Registration Statement on Form <FONT STYLE="white-space:nowrap">S-8</FONT> was previously filed with the Commission, including any post-effective amendments thereto (File <FONT STYLE="white-space:nowrap">No.&nbsp;333-281690)</FONT> (collectively,
  the &#147;<B><I>Prior Registration Statements</I></B>&#148;). Pursuant to General Instruction E to Form <FONT STYLE="white-space:nowrap">S-8,</FONT> the contents of the Prior Registration Statement are incorporated by reference into this
  Registration Statement, except that the provisions contained in Part II of such Prior Registration Statement are modified or supplemented, as the case may be, as set forth in this Registration Statement. </P>
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   <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>PART II </B></P>
  <P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>INFORMATION REQUIRED IN THE REGISTRATION STATEMENT </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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  <TR style = "page-break-inside:avoid">
  <TD WIDTH="10%" VALIGN="top" ALIGN="left"><B>ITEM&#8201;3.</B></TD>
  <TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left"><B>INCORPORATION OF DOCUMENTS BY REFERENCE. </B></P></TD></TR></TABLE>
  <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The Registrant hereby incorporates by reference into this Registration Statement the following documents previously filed by the Registrant
  with the Commission: </P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(a) Annual Report on <A HREF="http://www.sec.gov/Archives/edgar/data/1681087/000095017025042648/tecx-20241231.htm">Form
   <FONT STYLE="white-space:nowrap">10-K</FONT></A> for the fiscal year ended December&nbsp;31, 2024, filed with the Commission on March&nbsp;20, 2025; </P>
  <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(b) Current Reports on Form <FONT STYLE="white-space:nowrap">8-K,</FONT> which were filed with the Commission on <A HREF="http://www.sec.gov/Archives/edgar/data/../../../ix?doc=/Archives/edgar/data/1681087/000119312525016224/d817477d8k.htm">January
  <U></U>&nbsp;30, 2025</A> and <A HREF="http://www.sec.gov/Archives/edgar/data/../../../ix?doc=/Archives/edgar/data/1681087/000119312525018840/d843684d8k.htm">February<U></U>&nbsp;3, 2025</A> (except that, with respect to the foregoing Current
  Reports, any portions thereof which are furnished and not filed shall not be deemed incorporated by reference); and </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(b) the description
  of the Registrant&#146;s common stock in the Registrant&#146;s registration statement on <A HREF="http://www.sec.gov/Archives/edgar/data/1681087/000119312518195637/d562006d8a12b.htm">Form <FONT STYLE="white-space:nowrap">8-A</FONT></A> filed with
  the Commission on June&nbsp;11, 2018, including any amendments or reports filed for the purpose of updating such description, including as Exhibit 4.1 to the Registrant&#146;s Annual Report on Form <FONT STYLE="white-space:nowrap">10-K</FONT> for
  the fiscal year ended December&nbsp;31, 2024. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">All documents, reports and definitive proxy or information statements filed pursuant to
  Section&nbsp;13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended (the &#147;Exchange Act&#148;), other than current reports furnished under Item 2.02 or Item 7.01 of
  <FONT STYLE="white-space:nowrap">Form&nbsp;8-K&nbsp;and</FONT> exhibits furnished on such form that relate to such items, after the date of this Registration Statement and prior to the filing of a post-effective amendment which indicates that all
  securities offered hereby have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference into this Registration Statement and to be a part hereof from the date of filing of such documents;
  provided, however, that documents, reports and definitive proxy or information statements, or portions thereof, which are furnished and not filed in accordance with the rules of the Commission shall not be deemed incorporated by reference into this
  Registration Statement. Any statement contained in a document incorporated or deemed to be incorporated herein by reference shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement
  herein or in any other subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes that statement. Any such statement so modified or superseded shall not constitute a part of this Registration
  Statement, except as so modified or superseded. </P> <P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
  <TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
  <TR style = "page-break-inside:avoid">
  <TD WIDTH="10%" VALIGN="top" ALIGN="left"><B>ITEM&#8201;8.</B></TD>
  <TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left"><B>EXHIBITS. </B></P></TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
  <TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">
  
  
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  <TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"><B>Exhibit</B><br><B>Number</B></TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Description</B></P></TD></TR>
  
  
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  <TD VALIGN="top" NOWRAP>&#8199;4.1</TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/0001681087/000119312524200609/d878693dex31.htm">Fourth Amended and Restated Certificate of Incorporation, as amended through June<U></U>&nbsp;
  20, 2024 (incorporated by reference to Exhibit 3.1 to the Registrant&#146;s Quarterly Report on Form <FONT STYLE="white-space:nowrap">10-Q</FONT> (File No.<U></U><FONT STYLE="white-space:nowrap">&nbsp;
  001-38537),</FONT> filed with the Commission on August<U></U>&nbsp;14, 2024).</A></TD></TR>
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  <TD VALIGN="top" NOWRAP>&#8199;4.2</TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1681087/000119312518202460/d153924dex32.htm">Amended and Restated Bylaws (incorporated by reference to Exhibit 3.2 to the Registrant&#146;s Current Report on Form <FONT
  STYLE="white-space:nowrap">8-K</FONT> (File No.<U></U><FONT STYLE="white-space:nowrap">&nbsp;001-38537),</FONT> filed with the Commission on June<U></U>&nbsp;25, 2018).</A></TD></TR>
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  <TD VALIGN="top" NOWRAP>&#8199;5.1</TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top"><A HREF="d803448dex51.htm">Opinion of Cooley LLP. </A></TD></TR>
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  <TD HEIGHT="8" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top" NOWRAP>23.1</TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top"><A HREF="d803448dex231.htm">Consent of Deloitte&nbsp;&amp; Touche LLP, independent registered public accounting firm of Tectonic Therapeutic, Inc. </A></TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="8"></TD>
  <TD HEIGHT="8" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top" NOWRAP>23.2</TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top"><A HREF="d803448dex51.htm">Consent of Cooley LLP. Reference is made to Exhibit 5.1. </A></TD></TR></TABLE>
   <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">1 </P>
  
  </DIV></Center>
  
  
  <p style="margin-top:1em; margin-bottom:0em; page-break-before:always"> </p>
  <HR SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">
  
  
  <Center><DIV STYLE="width:8.5in" align="left">
  
  <TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">
  
  
  <TR>
  
  <TD></TD>
  
  <TD VALIGN="bottom" WIDTH="5%"></TD>
  <TD WIDTH="92%"></TD></TR>
  
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
  <TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"><B>Exhibit</B><br><B>Number</B></TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Description</B></P></TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="8"></TD>
  <TD HEIGHT="8" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top" NOWRAP>24.1</TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top"><A HREF="d803448ds8.htm#sig">Power of Attorney. Reference is made to the signature page hereto. </A></TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="8"></TD>
  <TD HEIGHT="8" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top" NOWRAP>99.1</TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1681087/000119312524164480/d852858dex106.htm">Tectonic Therapeutic, Inc. 2024 Equity Incentive Plan (incorporated by reference to Exhibit 10.6 to the Registrant&#146;s Current Report on Form
   <FONT STYLE="white-space:nowrap">8-K</FONT> (File No.<U></U><FONT STYLE="white-space:nowrap">&nbsp;001-38537),</FONT> filed with the Commission on June<U></U>&nbsp;20, 2024).</A></TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="8"></TD>
  <TD HEIGHT="8" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top" NOWRAP>99.2</TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1681087/000119312524164480/d852858dex107.htm">Forms of Option Grant Notice, Option Agreement and Notice of Exercise under Tectonic Therapeutic, Inc. 2024 Equity Incentive Plan (incorporated
   by reference to Exhibit 10.7 to the Registrant&#146;s Current Report on Form <FONT STYLE="white-space:nowrap">8-K</FONT> (File No.<U></U><FONT STYLE="white-space:nowrap">&nbsp;001-38537),</FONT> filed with the Commission on June<U></U>&nbsp;20,
  2024).</A></TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="8"></TD>
  <TD HEIGHT="8" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top" NOWRAP>99.3</TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1681087/000119312524164480/d852858dex108.htm">Tectonic Therapeutic, Inc. 2024 Employee Stock Purchase Plan (incorporated by reference to Exhibit 10.8 to the Registrant&#146;s Current Report
   on Form <FONT STYLE="white-space:nowrap">8-K</FONT> (File No.<U></U><FONT STYLE="white-space:nowrap">&nbsp;001-38537),</FONT> filed with the Commission on June<U></U>&nbsp;20, 2024).</A></TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="8"></TD>
  <TD HEIGHT="8" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top" NOWRAP>107</TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top"><A HREF="d803448dexfilingfees.htm">Filing Fee Table. </A></TD></TR>
  </TABLE> <P STYLE="font-size:18pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
  <TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
  <TR style = "page-break-inside:avoid">
  <TD WIDTH="10%" VALIGN="top" ALIGN="left"><B>ITEM&#8201;9.</B></TD>
  <TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left"><B>UNDERTAKINGS. </B></P></TD></TR></TABLE>
  <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(a) The undersigned Registrant hereby undertakes: </P>
  <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:9%; font-size:10pt; font-family:Times New Roman">(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this Registration Statement: </P>
  <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:13%; font-size:10pt; font-family:Times New Roman">(i) To include any prospectus required by Section&nbsp;10(a)(3) of the Securities Act of 1933, as amended (the &#147;Securities Act&#148;);
  </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:13%; font-size:10pt; font-family:Times New Roman">(ii) To reflect in the prospectus any facts or events arising after the effective date of the Registration Statement (or the most recent
  post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the Registration Statement. Notwithstanding the foregoing, any increase or decrease in volume of securities
  offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the
  Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the &#147;Calculation of Registration Fee&#148; table in the effective
  Registration Statement; </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:13%; font-size:10pt; font-family:Times New Roman">(iii) To include any material information with respect to the plan of distribution not previously disclosed in
  the Registration Statement or any material change to such information in the Registration Statement; </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><I>Provided, however,</I> that paragraphs (a)(1)(i)
  and (a)(1)(ii) do not apply if the Registration Statement is on Form <FONT STYLE="white-space:nowrap">S-8,</FONT> and the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or
  furnished to the Commission by the Registrant pursuant to Section&nbsp;13 or Section&nbsp;15(d) of the Exchange Act that are incorporated by reference in the Registration Statement; and </P>
  <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:9%; font-size:10pt; font-family:Times New Roman">(2) That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a
  new registration statement relating to the securities offered herein, and the offering of such securities at that time shall be deemed to be the initial<I> bona fide</I> offering thereof. </P>
  <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:9%; font-size:10pt; font-family:Times New Roman">(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the
  termination of the offering. </P>
   <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">2 </P>
  
  </DIV></Center>
  
  
  <p style="margin-top:1em; margin-bottom:0em; page-break-before:always"> </p>
  <HR SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">
  
  
  <Center><DIV STYLE="width:8.5in" align="left">
   <P STYLE="margin-top:0pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(b) The undersigned Registrant hereby undertakes that, for purposes of determining any
  liability under the Securities Act, each filing of the Registrant&#146;s annual report pursuant to Section&nbsp;13(a) or Section&nbsp;15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan&#146;s annual report
  pursuant to Section&nbsp;15(d) of the Exchange Act) that is incorporated by reference in the Registration Statement shall be deemed to be a new registration statement relating to the securities offered herein, and the offering of such securities at
  that time shall be deemed to be the initial<I> bona fide</I> offering thereof. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(c) Insofar as indemnification for liabilities arising
  under the Securities Act may be permitted to directors, officers and controlling persons of the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the Commission such indemnification
  is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a
  director, officer or controlling person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Registrant
  will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities
  Act and will be governed by the final adjudication of such issue. </P>
   <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">3 </P>
  
  </DIV></Center>
  
  
  <p style="margin-top:1em; margin-bottom:0em; page-break-before:always"> </p>
  <HR SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">
  
  
  <Center><DIV STYLE="width:8.5in" align="left">
   <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B><A NAME="sig"></A>SIGNATURES </B></P>
  <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe
  that it meets all of the requirements for filing on Form <FONT STYLE="white-space:nowrap">S-8</FONT> and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Watertown,
  Commonwealth of Massachusetts, on March&nbsp;20, 2025. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><DIV ALIGN="right">
  <TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">
  
  
  <TR>
  
  <TD WIDTH="5%"></TD>
  
  <TD VALIGN="bottom" WIDTH="1%"></TD>
  <TD WIDTH="94%"></TD></TR>
  
  
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top" COLSPAN="3"><B>TECTONIC THERAPEUTIC, INC.</B></TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="16"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="bottom">By</TD>
  <TD VALIGN="bottom" STYLE=" BORDER-BOTTOM:1px solid #000000">&nbsp;</TD>
  <TD VALIGN="bottom" STYLE="BORDER-BOTTOM:1px solid #000000"><I>/s/ Alise Reicin</I></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top"></TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="top">Alise Reicin</TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="bottom"></TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="bottom">President and Chief Executive Officer</TD></TR>
  </TABLE></DIV> <P STYLE="margin-top:24pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>POWER OF ATTORNEY </B></P>
  <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Alise Reicin and Daniel Lochner,
  and each of them, as true and lawful <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">attorneys-in-fact</FONT></FONT> and agents, with full powers of substitution and resubstitution, for them and in their name, place and stead, in
  any and all capacities, to sign any and all amendments (including post-effective amendments) to this registration statement, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and
  Exchange Commission, and generally to do all such things in their names and behalf in their capacities as officers and directors to enable Tectonic Therapeutic, Inc. to comply with the provisions of the Securities Act of 1933, as amended, and all
  requirements of the Securities and Exchange Commission, granting unto said <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">attorneys-in-fact</FONT></FONT> and agents, and each of them, full power and authority to do and perform
  each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he might or could do in person, ratifying and confirming all that said <FONT STYLE="white-space:nowrap"><FONT
  STYLE="white-space:nowrap">attorneys-in-fact</FONT></FONT> and agents, or any of them, or their or his substitutes or substitute, may lawfully do or cause to be done by virtue hereof. </P>
  <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Pursuant to the requirements of the Securities Act of 1933, as amended, this registration statement on Form
  <FONT STYLE="white-space:nowrap">S-8</FONT> has been signed by the following persons in the capacities and on the dates indicated. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
  <TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">
  
  
  <TR>
  
  <TD WIDTH="36%"></TD>
  
  <TD VALIGN="bottom"></TD>
  <TD WIDTH="47%"></TD>
  
  <TD VALIGN="bottom" WIDTH="1%"></TD>
  <TD WIDTH="15%"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
  <TD VALIGN="bottom" NOWRAP ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Signature</B></P></TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Title</B></P></TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Date</B></P></TD></TR>
  
  
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="16"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Alise Reicin</P>
  <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Alise Reicin</P></TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">President, Chief Executive Officer and Director</P>
  <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><I>(Principal Executive Officer)</I></P></TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="top" NOWRAP ALIGN="center">March&nbsp;20, 2025</TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="16"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Daniel Lochner</P>
  <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Daniel Lochner</P></TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Chief Financial Officer</P>
  <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><I>(Principal Financial Officer and Principal Accounting Officer)</I></P></TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="top" NOWRAP ALIGN="center">March&nbsp;20, 2025</TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="16"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Terrance McGuire</P>
  <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Terrance McGuire</P></TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top" ALIGN="center">Director</TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="top" NOWRAP ALIGN="center">March&nbsp;20, 2025</TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="16"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Phillip B. Donenberg</P>
  <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Phillip B. Donenberg</P></TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top" ALIGN="center">Director</TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="top" NOWRAP ALIGN="center">March&nbsp;20, 2025</TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="16"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Timothy A. Springer</P>
  <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Timothy A. Springer</P></TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top" ALIGN="center">Director</TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="top" NOWRAP ALIGN="center">March&nbsp;20, 2025</TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="16"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Praveen Tipirneni</P>
  <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Praveen Tipirneni</P></TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top" ALIGN="center">Director</TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="top" NOWRAP ALIGN="center">March&nbsp;20, 2025</TD></TR>
  <TR STYLE="font-size:1pt">
  <TD HEIGHT="16"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD>
  <TD HEIGHT="16" COLSPAN="2"></TD></TR>
  <TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
  <TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Stefan Vitorovic</P>
  <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">Stefan Vitorovic</P></TD>
  <TD VALIGN="bottom">&nbsp;&nbsp;</TD>
  <TD VALIGN="top" ALIGN="center">Director</TD>
  <TD VALIGN="bottom">&nbsp;</TD>
  <TD VALIGN="top" NOWRAP ALIGN="center">March&nbsp;20, 2025</TD></TR>
  </TABLE>
   <p STYLE="margin-top:0pt;margin-bottom:0pt ; font-size:8pt">&nbsp;</P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center">4 </P>
  
  </DIV></Center>
  
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metadata_filer: {"company-data": {"conformed-name": "Tectonic Therapeutic, Inc.", "cik": "0001681087", "assigned-sic": "2836", "organization-name": "03 Life Sciences", "irs-number": "810710585", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-285976", "film-number": "25757377"}, "business-address": {"street1": "490 ARSENAL WAY", "street2": "SUITE 210", "city": "WATERTOWN", "state": "MA", "zip": "02472", "phone": "(339) 666-3320"}, "mail-address": {"street1": "490 ARSENAL WAY", "street2": "SUITE 210", "city": "WATERTOWN", "state": "MA", "zip": "02472"}, "former-company": [{"former-conformed-name": "AVROBIO, Inc.", "date-changed": "20180131"}, {"former-conformed-name": "AvroBio, Inc.", "date-changed": "20160729"}]}
text: S-8
  As filed with the Securities and Exchange Commission on March 20, 2025
  Registration No. 333-
  UNITED STATES
  SECURITIES
  AND EXCHANGE COMMISSION
  Washington, D.C. 20549
  FORM
  S-8
  REGISTRATION STATEMENT
  UNDER
  THE
  SECURITIES ACT OF 1933
  Tectonic Therapeutic, Inc.
  (Exact name of registrant as specified in its charter)
  Delaware
  83-0710585
  (State or other jurisdiction of
  incorporation or organization)
  (I.R.S. Employer
  Identification No.)
  490 Arsenal Way
  Suite 210
  Watertown,
  MA
  02472
  (Address of Principal Executive Offices)
  (Zip Code)
  2024 Equity Incentive Plan
  2024 Employee Stock Purchase Plan
  (Full titles of the plans)
  Daniel Lochner
  Chief
  Financial Officer
  490 Arsenal Way
  Suite 210
  Watertown, MA
  02472
  (339)
  666-3320
  (Name, address, including zip code, and telephone number, including area code, of agent for service)
  Copies to:
  Divakar S. Gupta
  Brandon
  Fenn
  Minkyu Park
  Cooley LLP
  55 Hudson
  Yards
  New York, New York 10001
  (212)
  479-6000
  Indicate by
  check mark whether the registrant is a large accelerated filer, an accelerated filer, a
  non-accelerated
  filer, a smaller reporting company or an emerging growth company. See the definitions of "large
  accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule
  12b-2
  of the Exchange Act.
  Large accelerated filer
  ☐
  Accelerated Filer
  ☐
  Non-accelerated filer
  ☒
  Smaller reporting company
  ☒
  Emerging growth company
  ☐
  If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended
  transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐
  REGISTRATION OF ADDITIONAL SHARES PURSUANT TO GENERAL INSTRUCTION E
  Tectonic Therapeutic, Inc. (the "Registrant") is filing this Registration Statement on Form
  S-8
  with the Securities and Exchange commission (the "
  Commission
  ") for the purpose of registering (a) 742,815 shares of the Registrant's common stock, par value $0.0001 (the
  "
  Common Stock
  "), issuable to eligible persons under the Registrant's 2024 Equity Incentive Plan (the "
  2024 Plan
  "), pursuant to the provisions of the 2024 Plan providing for an automatic increase
  in the number of shares of Common Stock reserved and available for issuance under the 2024 Plan on January 1, 2025 and (b) 148,563 shares of Common Stock issuable to eligible persons under the Registrant's 2024 Employee Stock Purchase Plan
  (the "
  2024 ESPP
  "), pursuant to the provisions of the 2024 ESPP providing for an automatic increase in the number of shares of Common Stock reserved and available for issuance under the 2024 ESPP on January 1, 2025. In
  accordance with the instructional note to Part I of Form
  S-8
  as promulgated by the Commission, the information specified by Part I of the Form
  S-8
  has been omitted from
  this Registration Statement.
  These shares of Common Stock are additional securities of the same class as other securities for which the
  Registration Statement on Form
  S-8
  was previously filed with the Commission, including any post-effective amendments thereto (File
  No. 333-281690)
  (collectively,
  the "
  Prior Registration Statements
  "). Pursuant to General Instruction E to Form
  S-8,
  the contents of the Prior Registration Statement are incorporated by reference into this
  Registration Statement, except that the provisions contained in Part II of such Prior Registration Statement are modified or supplemented, as the case may be, as set forth in this Registration Statement.
  PART II
  INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  ITEM 3.
  INCORPORATION OF DOCUMENTS BY REFERENCE.
  The Registrant hereby incorporates by reference into this Registration Statement the following documents previously filed by the Registrant
  with the Commission:
  (a) Annual Report on
  Form
  10-K
  for the fiscal year ended December 31, 2024, filed with the Commission on March 20, 2025;
  (b) Current Reports on Form
  8-K,
  which were filed with the Commission on
  January
  30, 2025
  and
  February
  3, 2025
  (except that, with respect to the foregoing Current
  Reports, any portions thereof which are furnished and not filed shall not be deemed incorporated by reference); and
  (b) the description
  of the Registrant's common stock in the Registrant's registration statement on
  Form
  8-A
  filed with
  the Commission on June 11, 2018, including any amendments or reports filed for the purpose of updating such description, including as Exhibit 4.1 to the Registrant's Annual Report on Form
  10-K
  for
  the fiscal year ended December 31, 2024.
  All documents, reports and definitive proxy or information statements filed pursuant to
  Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), other than current reports furnished under Item 2.02 or Item 7.01 of
  Form 8-K and
  exhibits furnished on such form that relate to such items, after the date of this Registration Statement and prior to the filing of a post-effective amendment which indicates that all
  securities offered hereby have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference into this Registration Statement and to be a part hereof from the date of filing of such documents;
  provided, however, that documents, reports and definitive proxy or information statements, or portions thereof, which are furnished and not filed in accordance with the rules of the Commission shall not be deemed incorporated by reference into this
  Registration Statement. Any statement contained in a document incorporated or deemed to be incorporated herein by reference shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement
  herein or in any other subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes that statement. Any such statement so modified or superseded shall not constitute a part of this Registration
  Statement, except as so modified or superseded.
  ITEM 8.
  EXHIBITS.
  Exhibit
  Number
  Description
  4.1
  Fourth Amended and Restated Certificate of Incorporation, as amended through June
  20, 2024 (incorporated by reference to Exhibit 3.1 to the Registrant's Quarterly Report on Form
  10-Q
  (File No.
  001-38537),
  filed with the Commission on August
  14, 2024).
  4.2
  Amended and Restated Bylaws (incorporated by reference to Exhibit 3.2 to the Registrant's Current Report on Form
  8-K
  (File No.
  001-38537),
  filed with the Commission on June
  25, 2018).
  5.1
  Opinion of Cooley LLP.
  23.1
  Consent of Deloitte & Touche LLP, independent registered public accounting firm of Tectonic Therapeutic, Inc.
  23.2
  Consent of Cooley LLP. Reference is made to Exhibit 5.1.
  1
  Exhibit
  Number
  Description
  24.1
  Power of Attorney. Reference is made to the signature page hereto.
  99.1
  Tectonic Therapeutic, Inc. 2024 Equity Incentive Plan (incorporated by reference to Exhibit 10.6 to the Registrant's Current Report on Form
  8-K
  (File No.
  001-38537),
  filed with the Commission on June
  20, 2024).
  99.2
  Forms of Option Grant Notice, Option Agreement and Notice of Exercise under Tectonic Therapeutic, Inc. 2024 Equity Incentive Plan (incorporated
   by reference to Exhibit 10.7 to the Registrant's Current Report on Form
  8-K
  (File No.
  001-38537),
  filed with the Commission on June
  20,
  2024).
  99.3
  Tectonic Therapeutic, Inc. 2024 Employee Stock Purchase Plan (incorporated by reference to Exhibit 10.8 to the Registrant's Current Report
   on Form
  8-K
  (File No.
  001-38537),
  filed with the Commission on June
  20, 2024).
  107
  Filing Fee Table.
  ITEM 9.
  UNDERTAKINGS.
  (a) The undersigned Registrant hereby undertakes:
  (1) To file, during any period in which offers or sales are being made, a post-effective amendment to this Registration Statement:
  (i) To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933, as amended (the "Securities Act");
  (ii) To reflect in the prospectus any facts or events arising after the effective date of the Registration Statement (or the most recent
  post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the Registration Statement. Notwithstanding the foregoing, any increase or decrease in volume of securities
  offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the
  Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective
  Registration Statement;
  (iii) To include any material information with respect to the plan of distribution not previously disclosed in
  the Registration Statement or any material change to such information in the Registration Statement;
  Provided, however,
  that paragraphs (a)(1)(i)
  and (a)(1)(ii) do not apply if the Registration Statement is on Form
  S-8,
  and the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or
  furnished to the Commission by the Registrant pursuant to Section 13 or Section 15(d) of the Exchange Act that are incorporated by reference in the Registration Statement; and
  (2) That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a
  new registration statement relating to the securities offered herein, and the offering of such securities at that time shall be deemed to be the initial
  bona fide
  offering thereof.
  (3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the
  termination of the offering.
  2
  (b) The undersigned Registrant hereby undertakes that, for purposes of determining any
  liability under the Securities Act, each filing of the Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan's annual report
  pursuant to Section 15(d) of the Exchange Act) that is incorporated by reference in the Registration Statement shall be deemed to be a new registration statement relating to the securities offered herein, and the offering of such securities at
  that time shall be deemed to be the initial
  bona fide
  offering thereof.
  (c) Insofar as indemnification for liabilities arising
  under the Securities Act may be permitted to directors, officers and controlling persons of the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the Commission such indemnification
  is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a
  director, officer or controlling person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Registrant
  will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities
  Act and will be governed by the final adjudication of such issue.
  3
  SIGNATURES
  Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe
  that it meets all of the requirements for filing on Form
  S-8
  and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Watertown,
  Commonwealth of Massachusetts, on March 20, 2025.
  TECTONIC THERAPEUTIC, INC.
  By
  /s/ Alise Reicin
  Alise Reicin
  President and Chief Executive Officer
  POWER OF ATTORNEY
  KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Alise Reicin and Daniel Lochner,
  and each of them, as true and lawful
  attorneys-in-fact
  and agents, with full powers of substitution and resubstitution, for them and in their name, place and stead, in
  any and all capacities, to sign any and all amendments (including post-effective amendments) to this registration statement, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and
  Exchange Commission, and generally to do all such things in their names and behalf in their capacities as officers and directors to enable Tectonic Therapeutic, Inc. to comply with the provisions of the Securities Act of 1933, as amended, and all
  requirements of the Securities and Exchange Commission, granting unto said
  attorneys-in-fact
  and agents, and each of them, full power and authority to do and perform
  each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he might or could do in person, ratifying and confirming all that said
  attorneys-in-fact
  and agents, or any of them, or their or his substitutes or substitute, may lawfully do or cause to be done by virtue hereof.
  Pursuant to the requirements of the Securities Act of 1933, as amended, this registration statement on Form
  S-8
  has been signed by the following persons in the capacities and on the dates indicated.
  Signature
  Title
  Date
  /s/ Alise Reicin
  Alise Reicin
  President, Chief Executive Officer and Director
  (Principal Executive Officer)
  March 20, 2025
  /s/ Daniel Lochner
  Daniel Lochner
  Chief Financial Officer
  (Principal Financial Officer and Principal Accounting Officer)
  March 20, 2025
  /s/ Terrance McGuire
  Terrance McGuire
  Director
  March 20, 2025
  /s/ Phillip B. Donenberg
  Phillip B. Donenberg
  Director
  March 20, 2025
  /s/ Timothy A. Springer
  Timothy A. Springer
  Director
  March 20, 2025
  /s/ Praveen Tipirneni
  Praveen Tipirneni
  Director
  March 20, 2025
  /s/ Stefan Vitorovic
  Stefan Vitorovic
  Director
  March 20, 2025
  4