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