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