content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
    <headerData>
      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001944544</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0001877939</issuerCik>
        <issuerName>Castellum, Inc.</issuerName>
        <secFileNumber>001-41526</secFileNumber>
        <issuerAddress>
          <com:street1>1934 OLD GALLOWS ROAD</com:street1>
          <com:street2>SUITE 350</com:street2>
          <com:city>VIENNA</com:city>
          <com:stateOrCountry>VA</com:stateOrCountry>
          <com:zipCode>22182</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>(703) 752-6157</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Fuller Mark C</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Officer</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>First Georgetown Securites Inc</name>
          <address>
            <com:street1>Diagonal Rd Suite 200</com:street1>
            <com:city>Alexandria</com:city>
            <com:stateOrCountry>VA</com:stateOrCountry>
            <com:zipCode>22314</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>500000</noOfUnitsSold>
        <aggregateMarketValue>560000.00</aggregateMarketValue>
        <noOfUnitsOutstanding>86036874</noOfUnitsOutstanding>
        <approxSaleDate>05/19/2025</approxSaleDate>
        <securitiesExchangeName>NYSE</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>06/15/2019</acquiredDate>
        <natureOfAcquisitionTransaction>Private Placement</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CTM</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>500000</amountOfSecuritiesAcquired>
        <paymentDate>06/14/2019</paymentDate>
        <natureOfPayment>Cash/Check</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Mark C Fuller/Janice L Dud</name>
          <address>
            <com:street1>1934 Old Gallows Rd sutie 350</com:street1>
            <com:city>Vienna</com:city>
            <com:stateOrCountry>VA</com:stateOrCountry>
            <com:zipCode>22182</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>CTM</securitiesClassTitle>
        <saleDate>03/05/2025</saleDate>
        <amountOfSecuritiesSold>275000</amountOfSecuritiesSold>
        <grossProceeds>405752.95</grossProceeds>
      </securitiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Mark C Fuller/Janice L Dudley</name>
          <address>
            <com:street1>1934 Old Gallows Rd sutie 350, Vienna, V</com:street1>
            <com:city>Vienna</com:city>
            <com:stateOrCountry>VA</com:stateOrCountry>
            <com:zipCode>22182</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>CTM</securitiesClassTitle>
        <saleDate>03/06/2025</saleDate>
        <amountOfSecuritiesSold>225000</amountOfSecuritiesSold>
        <grossProceeds>296924.67</grossProceeds>
      </securitiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>05/19/2025</noticeDate>
        <signature>Carmen Zamores as a duly authorized representative of National Financial Services LLC, as attorney-in-fact for Fuller Mark C</signature>
      </noticeSignature>
    </formData>
  </edgarSubmission>
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text: 144
  0001944544
  XXXXXXXX
  LIVE
  0001877939
  Castellum, Inc.
  001-41526
  1934 OLD GALLOWS ROAD
  SUITE 350
  VIENNA
  VA
  22182
  (703) 752-6157
  Fuller Mark C
  Officer
  Common
  First Georgetown Securites Inc
  Diagonal Rd Suite 200
  Alexandria
  VA
  22314
  500000
  560000.00
  86036874
  05/19/2025
  NYSE
  Common
  06/15/2019
  Private Placement
  CTM
  N
  500000
  06/14/2019
  Cash/Check
  N
  Mark C Fuller/Janice L Dud
  1934 Old Gallows Rd sutie 350
  Vienna
  VA
  22182
  CTM
  03/05/2025
  275000
  405752.95
  Mark C Fuller/Janice L Dudley
  1934 Old Gallows Rd sutie 350, Vienna, V
  Vienna
  VA
  22182
  CTM
  03/06/2025
  225000
  296924.67
  05/19/2025
  Carmen Zamores as a duly authorized representative of National Financial Services LLC, as attorney-in-fact for Fuller Mark C