Dr Charles Forbin
Eric Braeden
Dr. Cleo Markham
Susan Clark
Secretary of State
Byron Morrow
Peterson
Lew Brown
Secretary of Defense
Sid McCoy
Dr. Chin
James Hong
First Scientist
Robert Cornthwaite
Thomas L. Harrison
Tom Basham
Russian Chairman
Leonid Rostoff
Translator
Serge Tschernisch
Military officer on phone (uncredited)
John Davey
Colossus (voice) (uncredited)
Paul Frees
The President
Gordon Pinsent
Military Computer Entry - Missile Launch (uncredited)
Fred Holliday
Scientist (uncredited)
Robert Quarry
Logan US Air Force (uncredited)
Don Ross
Party Guest (uncredited)
William Traylor
CIA Director Grauber
William Schallert
Dr. John F. Fisher
Georg Stanford Brown
Dr. Blake
Willard Sage
Dr. Kuprin
Alex Rodine
Dr. Jefferson J. Johnson
Martin E. Brooks
Angela Fields
Marion Ross
Missile Commander
Dolph Sweet
Original Music Composer
Michel Colombier
Director
Joseph Sargent
Costume Design
Edith Head
Screenplay
James Bridges
Makeup Artist
Bud Westmore
Art Direction
John J. Lloyd
Set Decoration
Ruby R. Levitt
John McCarthy Jr.
Assistant Director
Robin S. Clark
Sound
Terry Kellum
Ronald Pierce
Waldon O. Watson
Novel
D.F. Jones
Producer
Stanley Chase
Director of Photography
Gene Polito
Editor
Folmar Blangsted
Hairstylist
Larry Germain
Alexander Golitzen
Dialogue Coach
Bert Steinberger