Buster Crabbe as Flash Gordon

Carol Hughes as Dale Arden

Charles Middleton as Emperor Ming

Anne Gwynne as Sonja

Frank Shannon as Dr. Zarkov

John Hamilton as Professor Gordon

Herbert Rawlinson as Dr. Frohmann

Tom Chatterton as Professor Arden

Shirley Deane as Princess Aura

Lee Powell as Captain Roka

Roland Drew as Prince Barin

Don Rowan as Captain Torch

Victor Zimmerman as Lieutenant Thong

Edgar Edwards as Captain Turan

Michael Mark as Professor Karm

Earl Dwire as Janda

Harry C. Bradley as Keedish

Sigurd Nilssen as Count Korro

Mimi Taylor as Verna

Byron Foulger as Professor Drok

William Royle as Captain Sudan

Donald Curtis as Ronal (uncredited)

Luli Deste as Queen Fria (uncredited)

Ben Taggart as General Lupi (uncredited)

Allan Cavan as Man with Thinking Brain (uncredited)

Jack Roper as Man of Low Intellect (uncredited)

Reed Howes as Barin's Ship #5 Commander (uncredited)

Charles Sherlock as Guard Kroad (uncredited)

Mala as Prince of the Rock People (uncredited)

Chief Yowlachie as King of the Rock People (uncredited)

Jack Gardner as Professor Gordon's Radio Operator (uncredited)

Joey Ray as Professor Gordon's Assistant (uncredited)

Roy Barcroft as Ming's Soldier / Arborian Sentry (uncredited)

Lane Chandler as Ming's Soldier (uncredited)

Gene Rizzi as Ming's Soldier (uncredited)

Wheaton Chambers as Scientist (uncredited)

John Elliott as Scientist (uncredited)

Jack George as Scientist (uncredited)

Jean Brooks as Olga (uncredited)

Carmen D'Antonio as Ming's Dancing Girl (uncredited)

Vivian Mason as Ming's Gong Girl (uncredited)

Ernie Adams as (uncredited)

Clarice Sherry as (uncredited)

Tom Steele as Ming's Pilot (uncredited)

Eddie Parker as Arborian Prison Guard (uncredited)

Bill Hunter as Guard (uncredited)

Robert Blair as (uncredited)

Harold Daniels as (uncredited)

Pat Gleason as (uncredited)

Ernie Payson as (uncredited)

Paul Reed as (uncredited)

Charles Waldron Jr. as (uncredited)

Saul A. Goodkind as Various Characters (voice) (uncredited)