Buster Crabbe
Flash Gordon
Charles Middleton
Emperor Ming
John Hamilton
Professor Gordon
Herbert Rawlinson
Dr. Frohmann
Tom Chatterton
Professor Arden
Shirley Deane
Princess Aura
Victor Zimmerman
Lieutenant Thong
Edgar Edwards
Captain Turan
Michael Mark
Professor Karm
Sigurd Nilssen
Count Korro
Byron Foulger
Professor Drok
William Royle
Captain Sudan
Donald Curtis
Ronal (uncredited)
Luli Deste
Queen Fria (uncredited)
Ben Taggart
General Lupi (uncredited)
Allan Cavan
Man with Thinking Brain (uncredited)
Jack Roper
Man of Low Intellect (uncredited)
Reed Howes
Barin's Ship #5 Commander (uncredited)
Charles Sherlock
Guard Kroad (uncredited)
Mala
Prince of the Rock People (uncredited)
Chief Yowlachie
King of the Rock People (uncredited)
Jack Gardner
Professor Gordon's Radio Operator (uncredited)
Joey Ray
Professor Gordon's Assistant (uncredited)
Roy Barcroft
Ming's Soldier / Arborian Sentry (uncredited)
Lane Chandler
Ming's Soldier (uncredited)
Gene Rizzi
Ming's Soldier (uncredited)
Wheaton Chambers
Scientist (uncredited)
John Elliott
Scientist (uncredited)
Jack George
Scientist (uncredited)
Jean Brooks
Olga (uncredited)
Carmen D'Antonio
Ming's Dancing Girl (uncredited)
Vivian Mason
Ming's Gong Girl (uncredited)
Clarice Sherry
(uncredited)
Tom Steele
Ming's Pilot (uncredited)
Eddie Parker
Arborian Prison Guard (uncredited)
Bill Hunter
Guard (uncredited)
Harold Daniels
(uncredited)
Charles Waldron Jr.
(uncredited)
Saul A. Goodkind
Various Characters (voice) (uncredited)