Michael Caine
Brad Crane
Katharine Ross
Helena
Richard Widmark
General Slater
Richard Chamberlain
Dr. Hubbard
Olivia de Havilland
Maureen
Ben Johnson
Felix
Lee Grant
Anne MacGregor
José Ferrer
Dr. Andrews
Patty Duke
Rita
Slim Pickens
Jud Hawkins
Bradford Dillman
Major Baker
Fred MacMurray
Clarence
Henry Fonda
Dr. Krim
Cameron Mitchell
General Thompson
Christian Juttner
Paul Durant
Morgan Paull
Dr. Newman
Alejandro Rey
Dr. Martinez
Don 'Red' Barry
Pete Harris
Elizabeth Rogers
Woman Scientist
Doria Cook-Nelson
Mrs. Durant
Robert Varney
Mr. Durant
Ernie F. Orsatti
Duty Officer
Patrick Culliton
Sheriff Morrison
John Furlong
Cameraman
Chris Petersen
Hal
Jerry Toomey
Eddie
Barbara Costello
Receptionist / Nurse
Jenifer Taurins
Nurse
David Himes
Radioman
Mara Cook
Secretary
Joey Eisnach
Bee Boy
Stephen Powers
Radarman
Chris Capen
Lieutenant
Tony Haig
Officer #2
Bill Snider
Radarman #2
George Simmons
Nurse
Arell Blanton
Sergeant
Trent Dolan
Radio Sergeant
John Williams
Launching Officer
Steven Marlo
Pilot #1
Phil Montgomery
Mechanic
Jim Galante
Doctor
Frank Blair
Frank Blair
Marcia Nicholson
Captain
Arthur Space
Engineer
Chuck Hayward
Standby Engineer
Glenn Charles Lewis
Chemical Warfare Guard
Art Balinger
Radio Announcer
Michael Sheehan
Airman #1
Howard Culver
Airman #2
Buzz Barbee
Briefing Guest (uncredited)
Ken Clayton
Dr. Moore (uncredited)
Marneen Fields
Train Passenger (uncredited)
Bob Harks
Townsman (uncredited)
Mike Johnson
Burning Man (uncredited)
Jack Krupnick
Train Passenger (uncredited)
Lawrence Moran
Colonel's Son (uncredited)
Monty O'Grady
Briefing Guest (uncredited)
John Otrin
Wild Lines (uncredited)
Leoda Richards
Briefing Guest (uncredited)
Norman Stevans
Briefing Guest (uncredited)