Joaquin Phoenix

Theodore

Scarlett Johansson

Samantha (voice)

Lynn Adrianna

Letter Writer #1

Lisa Renee Pitts

Letter Writer #2

Gabe Gomez

Letter Writer #3

Chris Pratt

Paul

Artt Butler

Text Voice (voice)

May Lindstrom

Sexy Pregnant TV Star

Rooney Mara

Catherine

Bill Hader

Chat Room Friend #2 (voice)

Kristen Wiig

SexyKitten (voice)

Brian D. Johnson

OS1 Commercial Lead

Amy Adams

Amy

Matt Letscher

Charles

Spike Jonze

Alien Child (voice)

Olivia Wilde

Blind Date

David Azar

Theodore's Divorce Attorney

Guy Lewis

Marriage Counselor

Melanie Seacat

Nice Lady

Pramod Kumar

Pizza Vendor

Evelyn Edwards

Mother Who Dated Pricks

Steve Zissis

New Sweet Boyfriend of Mother Who Dated Pricks

Dane White

Son

Nicole Grother

Daughter

James Ozasky

Catherine's Dad

Samantha Sarakanti

Mother of Newborn

Luka Jones

Lewman

Gracie Prewitt

Jocelyn (Birthday Girl)

Claudia Choi

Uncomfortable Waitress

Laura Kai Chen

Tatiana

Portia Doubleday

Surrogate Date Isabella

Soko

Isabella (voice)

Wendy Leon

Grocery Shopper

Lil Buck

Busker / Dancer

Robert Benard

Michael Wadsworth (Editor)

Lisa Cohen

Michael Wadsworth's Wife

Grant Samson

Michael Wadsworth's Associate

Brian Cox

Alan Watts (voice)

Alia Janine

Commuter (uncredited)