Dalton Trumbo
Cleo Trumbo
Hedda Hopper
Nikola Trumbo
Arlen Hird
Frank King
Edward G. Robinson
John Wayne
Buddy Ross
Ed Muhl
Sam Wood
Ian McLellan Hunter
J. Parnell Thomas
Louis B. Mayer
Virgil Brooks
Hymie King
Chris Trumbo (Age 13-17)
Kirk Douglas
Andrew Hird
Otto Preminger
Roy Brewer
Chris Trumbo (age 6-10) (as Tobias McDowell Nichols)
Himself (archive footage)
Party Goer
Niki Trumbo (age 8-11)
Robert Stripling
Reporter
Robert Kenny
Jury Foreman
Jeff Krandall
Mitzi Trumbo (age 6-8)
Mitzi Trumbo (age 9-12)
Edward 'Ed' Muhl
Starlet (uncredited)
Ethel (uncredited)
Showgirl (uncredited)
Trumbo Friend (uncredited)
Juror (uncredited)