<SEC-DOCUMENT>0001451505-15-000143.txt : 20150923
<SEC-HEADER>0001451505-15-000143.hdr.sgml : 20150923
<ACCEPTANCE-DATETIME>20150923164145
ACCESSION NUMBER:		0001451505-15-000143
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20150923
FILED AS OF DATE:		20150923
DATE AS OF CHANGE:		20150923

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Transocean Ltd.
		CENTRAL INDEX KEY:			0001451505
		STANDARD INDUSTRIAL CLASSIFICATION:	DRILLING OIL & GAS WELLS [1381]
		IRS NUMBER:				980599916
		STATE OF INCORPORATION:			V8
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		BLANDONNET INTERNATIONAL BUSINESS CENTER
		STREET 2:		BLDG F, 7TH FLOOR, CHEMIN DE BLANDONNET
		CITY:			VERNIER
		STATE:			V8
		ZIP:			1214
		BUSINESS PHONE:		41-58-792-9243

	MAIL ADDRESS:	
		STREET 1:		BLANDONNET INTERNATIONAL BUSINESS CENTER
		STREET 2:		BLDG F, 7TH FLOOR, CHEMIN DE BLANDONNET
		CITY:			VERNIER
		STATE:			V8
		ZIP:			1214

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Sjobring Lars
		CENTRAL INDEX KEY:			0001411431

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-53533
		FILM NUMBER:		151121439

	MAIL ADDRESS:	
		STREET 1:		C/O AUTOLIV INC.
		STREET 2:		VASAGATAN 11, 7TH FL
		CITY:			STOCKHOLM
		STATE:			V7
		ZIP:			SE-111 20
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_144304089556385.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-09-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001451505</issuerCik>
        <issuerName>Transocean Ltd.</issuerName>
        <issuerTradingSymbol>RIG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001411431</rptOwnerCik>
            <rptOwnerName>Sjobring Lars</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>10 CHEMIN DE BLANDONNET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GENEVA, SWITZERLAND</rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode>1214</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP and General Counsel</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Registered Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2015-09-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5324</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>14.40</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/Jill S. Greene By Power of Attorney</signatureName>
        <signatureDate>2015-09-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
