Reparto
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
Paul Frees
Alien (voice)
Frank Wilcox
Alfred Cassidy
Larry J. Blake
Motorcycle cop
Forbes Murray
Military Officer at Experiment
Arthur Tovey
Officer/Civilian at Military Conference
Charles Evans
Dr. Alberts (uncredited)
Paul Frees
Alien (voice) (uncredited)
Clark Howat
Sgt. Nash (uncredited)
Harry Lauter
Cutting - Generator Technician (uncredited)
Sol Murgi
Plane Passenger (uncredited)
Forbes Murray
Military Officer at Experiment (uncredited)
Mike Ragan
Tank Commander (uncredited)
Dale Van Sickel
Man Crushed Beneath Wall (uncredited)
Frank Wilcox
Alfred Cassidy (uncredited)
William Woodson
Narrator (voice) (uncredited)
