<SEC-DOCUMENT>0001140361-12-053032.txt : 20121228
<SEC-HEADER>0001140361-12-053032.hdr.sgml : 20121228
<ACCEPTANCE-DATETIME>20121228164136
ACCESSION NUMBER:		0001140361-12-053032
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20121220
FILED AS OF DATE:		20121228
DATE AS OF CHANGE:		20121228

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Prothena Corp plc
		CENTRAL INDEX KEY:			0001559053
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			L2
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		25-28 NORTH WALL QUAY
		CITY:			DUBLIN
		STATE:			L2
		ZIP:			DUBLIN 1
		BUSINESS PHONE:		353 1 709 4700

	MAIL ADDRESS:	
		STREET 1:		25-28 NORTH WALL QUAY
		CITY:			DUBLIN
		STATE:			L2
		ZIP:			DUBLIN 1

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Neotope Corp Ltd
		DATE OF NAME CHANGE:	20120926

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ELAN CORP PLC
		CENTRAL INDEX KEY:			0000737572
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-35676
		FILM NUMBER:		121291365

	BUSINESS ADDRESS:	
		STREET 1:		TREASURY BUILDING
		STREET 2:		LOWER GRAND CANAL STREET
		CITY:			DUBLIN 2
		STATE:			L2
		ZIP:			00000
		BUSINESS PHONE:		35317094000

	MAIL ADDRESS:	
		STREET 1:		TREASURY BUILDING
		STREET 2:		LOWER GRAND CANAL STREET
		CITY:			DUBLIN 2
		STATE:			L2
		ZIP:			00000

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Elan Science One Ltd
		CENTRAL INDEX KEY:			0001565579
		STATE OF INCORPORATION:			L2
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-35676
		FILM NUMBER:		121291364

	BUSINESS ADDRESS:	
		STREET 1:		TREASURY BUILDING
		STREET 2:		LOWER GRAND CANAL STREET
		CITY:			DUBLIN
		STATE:			L2
		ZIP:			DUBLIN 2
		BUSINESS PHONE:		353 1 709 4000

	MAIL ADDRESS:	
		STREET 1:		TREASURY BUILDING
		STREET 2:		LOWER GRAND CANAL STREET
		CITY:			DUBLIN
		STATE:			L2
		ZIP:			DUBLIN 2
</SEC-HEADER>
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<TYPE>3
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<DESCRIPTION>FORM 3
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    <periodOfReport>2012-12-20</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001559053</issuerCik>
        <issuerName>Prothena Corp plc</issuerName>
        <issuerTradingSymbol>PRTA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000737572</rptOwnerCik>
            <rptOwnerName>ELAN CORP PLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>TREASURY BUILDING,</rptOwnerStreet1>
            <rptOwnerStreet2>LOWER GRAND CANAL STREET</rptOwnerStreet2>
            <rptOwnerCity>DUBLIN 2</rptOwnerCity>
            <rptOwnerState>L2</rptOwnerState>
            <rptOwnerZipCode>00000</rptOwnerZipCode>
            <rptOwnerStateDescription>IRELAND</rptOwnerStateDescription>
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        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
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    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001565579</rptOwnerCik>
            <rptOwnerName>Elan Science One Ltd</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>TREASURY BUILDING</rptOwnerStreet1>
            <rptOwnerStreet2>LOWER GRAND CANAL STREET</rptOwnerStreet2>
            <rptOwnerCity>DUBLIN</rptOwnerCity>
            <rptOwnerState>L2</rptOwnerState>
            <rptOwnerZipCode>DUBLIN 2</rptOwnerZipCode>
            <rptOwnerStateDescription>IRELAND</rptOwnerStateDescription>
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        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Ordinary Shares</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3182253</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Indirect</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Shares directly owned by Elan Science One Limited (&quot;ES1&quot;). ES1 is an indirect wholly-owned subsidiary of Elan Corporation, plc.</footnote>
    </footnotes>

    <remarks>Exhibit List:  Exhibit 99.1 - Joint Filer Information</remarks>

    <ownerSignature>
        <signatureName>/s/ William F. Daniel, Executive Vice President and Company Secretary</signatureName>
        <signatureDate>2012-12-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
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