Elle Fanning Niki Trumbo
Bryan Cranston Dalton Trumbo
Diane Lane Cleo Trumbo
Audrey Hepburn Princess Ann (archive footage) (uncredited)
Alan Tudyk Ian McLellan Hunter
Helen Mirren Hedda Hopper
John Goodman Frank King
Michael Stuhlbarg Edward G. Robinson
Stephen Root Hymie King
James Garner Self (archive footage) (uncredited)
Dan Bakkedahl Roy Brewer
Lucille Ball Self (archive footage) (voice) (uncredited)
Jay Roach Director, Producer
Eddie Albert Irving Radovich in Roman Holiday (archive footage) (uncredited)
Jean Simmons Varinia (archive footage) (uncredited)
Adewale Akinnuoye-Agbaje Virgil Brooks
Ronald Reagan Self (archive footage) (uncredited)
Deborah Kerr Self (archive footage) (uncredited)
Robert Taylor Self (archive footage) (uncredited)
Danny Kaye Self (archive footage) (uncredited)
Louis C.K. Arlen Hird
Sean Bridgers Jeff Krandall
Richard Portnow Louis B. Mayer
Dean O'Gorman Kirk Douglas
John Getz Sam Wood
Michael London Producer
Madison Wolfe Niki Trumbo (age 8-11)
Laurence Olivier Crassus (archive footage) (uncredited)
Gregory Peck Joe Bradley (archive footage) (uncredited)
Cary Grant Self (archive footage) (uncredited)
Roger Bart Buddy Ross
Alan Baumgarten Editor
Christian Berkel Otto Preminger
Dane Rhodes Reporter
Mark Harelik Ed Muhl, Edward 'Ed' Muhl
Peter MacKenzie Robert Kenny
James DuMont J. Parnell Thomas
Mark Ricker Production Design
Johnny Sneed Robert Stripling
Lauren Bacall Self (archive footage) (uncredited)
Gary Archer Prosthetics
Garrett Hines Andrew Hird
Janice Williams Producer
Dalton Trumbo Himself (archive footage)
Theodore Shapiro Original Music Composer
Toby Nichols Chris Trumbo (age 6-10) (as Tobias McDowell Nichols)
David James Elliott John Wayne
David Rubin Casting
John McNamara Screenplay, Producer
Meghan Wolfe Mitzi Trumbo (age 6-8)
Mattie Liptak Chris Trumbo (Age 13-17)
Daniel Orlandi Costume Designer
Jesse Rosenthal Art Direction
Geoffrey Haley "A" Camera Operator, Steadicam Operator
Jeri Habberstad Stunt Double
John Neisler Jury Foreman
Laura Flannery Party Goer
Rio Hackford Reporter
Monica Levinson Producer, Unit Production Manager
Jim Denault Director of Photography
Kevin Kelly Brown Producer
George Parra First Assistant Director
Heather Arthur Stunt Coordinator
Scott August Second Assistant Director
Shivani Rawat Producer
Jaclyn Bethany Starlet (uncredited)
Cindy Carr Set Decoration
Nimitt Mankad Producer
Rhonda Laizer Trumbo Friend (uncredited)
Michelle Graham Co-Producer
Veronica Parks Showgirl (uncredited)
Suzanne LaChasse Showgirl (uncredited)