Bryan Cranston

Dalton Trumbo

Diane Lane

Cleo Trumbo

Helen Mirren

Hedda Hopper

Elle Fanning

Nikola Trumbo

Louis C.K.

Arlen Hird

John Goodman

Frank King

Michael Stuhlbarg

Edward G. Robinson

David James Elliott

John Wayne

Roger Bart

Buddy Ross

Mark Harelik

Ed Muhl

John Getz

Sam Wood

Alan Tudyk

Ian McLellan Hunter

James DuMont

J. Parnell Thomas

Richard Portnow

Louis B. Mayer

Adewale Akinnuoye-Agbaje

Virgil Brooks

Stephen Root

Hymie King

Mattie Liptak

Chris Trumbo (Age 13-17)

Dean O'Gorman

Kirk Douglas

Garrett Hines

Andrew Hird

Christian Berkel

Otto Preminger

Dan Bakkedahl

Roy Brewer

Toby Nichols

Chris Trumbo (age 6-10) (as Tobias McDowell Nichols)

Dalton Trumbo

Himself (archive footage)

Laura Flannery

Party Goer

Madison Wolfe

Niki Trumbo (age 8-11)

Johnny Sneed

Robert Stripling

Rio Hackford

Reporter

Dane Rhodes

Reporter

Peter MacKenzie

Robert Kenny

John Neisler

Jury Foreman

Sean Bridgers

Jeff Krandall

Meghan Wolfe

Mitzi Trumbo (age 6-8)

Becca Nicole Preston

Mitzi Trumbo (age 9-12)

Jaclyn Bethany

Starlet (uncredited)

Kate Kuen

Ethel (uncredited)

Suzanne LaChasse

Showgirl (uncredited)

Rhonda Laizer

Trumbo Friend (uncredited)

Veronica Parks

Showgirl (uncredited)

Anne Speed

Juror (uncredited)

Eddie Albert

Irving Radovich in Roman Holiday (archive footage) (uncredited)

Lauren Bacall

Self (archive footage) (uncredited)

Lucille Ball

Self (archive footage) (voice) (uncredited)

James Garner

Self (archive footage) (uncredited)

Cary Grant

Self (archive footage) (uncredited)

Laurence Olivier

Crassus (archive footage) (uncredited)