<SEC-DOCUMENT>0000949157-25-000032.txt : 20250325
<SEC-HEADER>0000949157-25-000032.hdr.sgml : 20250325
<ACCEPTANCE-DATETIME>20250325184838
ACCESSION NUMBER:		0000949157-25-000032
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20250321
FILED AS OF DATE:		20250325
DATE AS OF CHANGE:		20250325

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Trpkovski Peter A
		CENTRAL INDEX KEY:			0001980271
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34474
		FILM NUMBER:		25769649

	MAIL ADDRESS:	
		STREET 1:		CENTURY ALUMINUM COMPANY
		STREET 2:		1 S. WACKER DRIVE, SUITE 1000
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CENTURY ALUMINUM CO
		CENTRAL INDEX KEY:			0000949157
		STANDARD INDUSTRIAL CLASSIFICATION:	PRIMARY PRODUCTION OF ALUMINUM [3334]
		ORGANIZATION NAME:           	04 Manufacturing
		EIN:				133070826
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1 SOUTH WACKER DRIVE
		STREET 2:		SUITE 1000
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
		BUSINESS PHONE:		3126963101

	MAIL ADDRESS:	
		STREET 1:		1 SOUTH WACKER DRIVE
		STREET 2:		SUITE 1000
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wk-form4_1742942912.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-03-21</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000949157</issuerCik>
        <issuerName>CENTURY ALUMINUM CO</issuerName>
        <issuerTradingSymbol>CENX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001980271</rptOwnerCik>
            <rptOwnerName>Trpkovski Peter A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CENTURY ALUMINUM COMPANY</rptOwnerStreet1>
            <rptOwnerStreet2>1 S. WACKER DRIVE, SUITE 1000</rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60606</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, CFO and Treasurer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2025-03-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>12455</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>65491</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents TVSUs granted to the Reporting Person in connection with his promotion to the role of EVP, CFO and Treasurer,  all of which will vest on December 31, 2027, subject to the grant's terms and conditions.</footnote>
        <footnote id="F2">Includes unvested TVSUs granted to the Reporting Person under the Issuer's Long-Term Incentive Plans.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Paul Sharobeem, as attorney in fact for Peter A. Trpkovski</signatureName>
        <signatureDate>2025-03-25</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
