Eddie Albert
Adm. Wiley Sloan
John Carradine
Ronald Bentley
Alex Cord
Dr. Sam Marlowe
Robert Forster
Comdr. Jeff Selkirk
Frank Gorshin
Dan Wesker
Mark Harmon
Peter Cabot
Christopher Lee
John McKenzie
Tom Dunstan
Agra Worker
Bruce Heighley
Technician
Robert Paul Jordan
(voice)
Jean Marsh
Dr. Goldman
John McIntire
Sen. Oliver Bartholomew
Jeanette Nolan
Sarah Bartholomew
Duncan Regehr
Paul Ryker
Emma Samms
Lea McKenzie
Alan Fudge
Lew Bascomb
George Innes
Dave Winter
John Ratzenberger
Bill Sweeney
Julie Bennett
Sylvia King
John Berwick
Crewman
Kirk Cameron
Liam
Colin Drake
Old Man
Michael Evans
Eric Whittaker
Hedley Mattingly
Bailey
Belinda Mayne
Sally Crane
Christina Nigra
Beth
Sandy Simpson
Moore
Warwick Sims
Luke Crane
Peter von Zerneck
Hoffman
Michael White
PC18 Officer
Lawrence Benedict
Young Bailey (uncredited)
John Brandon
Chief Engineer (uncredited)
Alan Caillou
Goliath Captain (uncredited)
Laurence Haddon
Cpt. Volero (uncredited)
Irene Hervey
Carrie (uncredited)
Lori Lethin
Maria (uncredited)
Kip Niven
Gantman (uncredited)
Clete Roberts
Newscaster (uncredited)
Peter Stader
Ed Linder (uncredited)
Laird Stuart
Paul (uncredited)
Michael M. Vendrell
Robbie Cole (uncredited)
Tom Willett
Lambeth Walk Dancer (uncredited)
Lawrence Levine
(uncredited)