<SUBMISSION>
<ACCESSION-NUMBER>0001179110-07-009929
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20070510
<FILING-DATE>20070514
<DATE-OF-FILING-DATE-CHANGE>20070514
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>LIBERTY MEDIA CORP
<CIK>0001355096
<ASSIGNED-SIC>4841
<IRS-NUMBER>841288730
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>12300 LIBERTY BOULEVARD
<CITY>ENGLEWOOD
<STATE>CO
<ZIP>80112
<PHONE>7208755400
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>12300 LIBERTY BOULEVARD
<CITY>ENGLEWOOD
<STATE>CO
<ZIP>80112
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>Liberty Media Holding CORP
<DATE-CHANGED>20060303
</FORMER-COMPANY>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>RAPLEY DAVID E
<CIK>0001195192
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-51990
<FILM-NUMBER>07845303
</FILING-VALUES>
<BUSINESS-ADDRESS>
<PHONE>3038148762
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>720 EAST RIM ROAD
<CITY>FRANKTOWN
<STATE>CO
<ZIP>80116
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-05-10</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001355096</issuerCik>
        <issuerName>LIBERTY MEDIA CORP</issuerName>
        <issuerTradingSymbol>LCAP; LINT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001195192</rptOwnerCik>
            <rptOwnerName>RAPLEY DAVID E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>12300 LIBERTY BLVD.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ENGLEWOOD</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80112</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>116.17</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-05-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1310</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-05-10</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Series A Liberty Capital Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1310</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1310</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>24.80</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-05-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5710</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-05-10</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Series A Liberty Interactive Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5710</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5710</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The stock option will vest in full on the date of the first annual stockholders meeting of the Issuer after the date of the grant, subject to the early vesting provisions of the applicable award agreement.</footnote>
    </footnotes>

    <remarks>The trading symbols for the Issuer's Series A and Series B Liberty Capital Common Stock are LCAPA and LCAPB, respectively, and for the Issuer's Series A and Series B Liberty Interactive Common Stock are LINTA and LINTB, respectively.</remarks>

    <ownerSignature>
        <signatureName>/s/ David E. Rapley</signatureName>
        <signatureDate>2007-05-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
