Katharine Ross
Capt. Helena Anderson
Richard Widmark
Gen. Thaddeus Slater
Richard Chamberlain
Dr. Hubbard
Olivia de Havilland
Maureen Schuester
Bradford Dillman
Maj. Baker
Fred MacMurray
Maj. Clarance Tuttle
Henry Fonda
Dr. Walter Krim
Cameron Mitchell
Gen. Thompson
Christian Juttner
Paul Durant
Alejandro Rey
Dr. Martinez
Don 'Red' Barry
Pete Harris
Elizabeth Rogers
Woman Scientist
Doria Cook-Nelson
Mrs. Durant
Ernie F. Orsatti
Duty Officer
Patrick Culliton
Sheriff Morrison
Barbara Costello
Receptionist / Nurse
Trent Dolan
Radio Sergeant
John Williams
Launching Officer
Chuck Hayward
Standby Engineer
Glenn Charles Lewis
Chemical Warfare Guard
Art Balinger
Radio Announcer
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)
