Hugh Marlowe
Dr. Russell A. Marvin
Joan Taylor
Carol Marvin
Donald Curtis
Maj. Huglin
Morris Ankrum
Brig. Gen. John Hanley
Thomas Browne Henry
Vice Adm. Enright
Grandon Rhodes
Gen. Edmunds
John Zaremba
Prof. Kanter
Sydney Mason
Frank the garage man
Larry J. Blake
Motorcycle cop
Bert Stevens
Air Intelligence Command Officer
Arthur Tovey
Officer/Civilian at Military Conference
Alan Wells
Major Kimberly
Nicky Blair
Military Officer at Experiment (uncredited)
Jimmy Cross
Military Messenger (uncredited)
Jack Deery
Military Officer (uncredited)
Charles Evans
Dr. Alberts (uncredited)
Raoul Freeman
Military Official (uncredited)
Paul Frees
Alien (voice) (uncredited)
James Gonzalez
Military Official (uncredited)
Duke Green
Minor Role (uncredited)
Ed Haskett
Military Official (uncredited)
Clark Howat
Sgt. Nash (uncredited)
Harry Lauter
Cutting - Generator Technician (uncredited)
Don Marlowe
Minor Role (uncredited)
William Meader
Worker in Control Tower (uncredited)
Sol Murgi
Plane Passenger (uncredited)
Forbes Murray
Military Officer at Experiment (uncredited)
William J. O'Brien
Radio Listener (archive footage) (uncredited)
Murray Pollack
Plane Passenger (uncredited)
Mike Ragan
Tank Commander (uncredited)
Alan Reynolds
Maj. Kimberly (uncredited)
Dale Van Sickel
Man Crushed Beneath Wall (uncredited)
Guy Way
Civilian Observing Saucer Attack (uncredited)
Bob Whitney
Plane Passenger (uncredited)
Frank Wilcox
Alfred Cassidy (uncredited)
Beal Wong
Chinese Radio Listener (uncredited)
William Woodson
Narrator (voice) (uncredited)