Hugh Marlowe

Character: Dr. Russell A. Marvin

Joan Taylor

Character: Carol Marvin

Donald Curtis

Character: Maj. Huglin

Morris Ankrum

Character: Brig. Gen. John Hanley

Thomas Browne Henry

Character: Vice Adm. Enright

Grandon Rhodes

Character: Gen. Edmunds

John Zaremba

Character: Prof. Kanter

Paul Frees

Character: Alien (voice)

Frank Wilcox

Character: Alfred Cassidy

Sydney Mason

Character: Frank the garage man

Larry J. Blake

Character: Motorcycle cop

Bert Stevens

Character: Air Intelligence Command Officer

Forbes Murray

Character: Military Officer at Experiment

Arthur Tovey

Character: Officer/Civilian at Military Conference

Alan Wells

Character: Major Kimberly

Nicky Blair

Character: Military Officer at Experiment (uncredited)

Jimmy Cross

Character: Military Messenger (uncredited)

Jack Deery

Character: Military Officer (uncredited)

Charles Evans

Character: Dr. Alberts (uncredited)

Raoul Freeman

Character: Military Official (uncredited)

Paul Frees

Character: Alien (voice) (uncredited)

James Gonzalez

Character: Military Official (uncredited)

Duke Green

Character: Minor Role (uncredited)

Ed Haskett

Character: Military Official (uncredited)

Clark Howat

Character: Sgt. Nash (uncredited)

Harry Lauter

Character: Cutting - Generator Technician (uncredited)

Don Marlowe

Character: Minor Role (uncredited)

William Meader

Character: Worker in Control Tower (uncredited)

Sol Murgi

Character: Plane Passenger (uncredited)

Forbes Murray

Character: Military Officer at Experiment (uncredited)

William J. O'Brien

Character: Radio Listener (archive footage) (uncredited)

Murray Pollack

Character: Plane Passenger (uncredited)

Mike Ragan

Character: Tank Commander (uncredited)

Alan Reynolds

Character: Maj. Kimberly (uncredited)

Dale Van Sickel

Character: Man Crushed Beneath Wall (uncredited)

Guy Way

Character: Civilian Observing Saucer Attack (uncredited)

Bob Whitney

Character: Plane Passenger (uncredited)

Frank Wilcox

Character: Alfred Cassidy (uncredited)

Beal Wong

Character: Chinese Radio Listener (uncredited)

William Woodson

Character: Narrator (voice) (uncredited)