Roddy McDowall
Role: Cornelius
Bradford Dillman
Role: Dr. Lewis Dixon
Natalie Trundy
Role: Dr. Stephanie 'Stevie' Branton
Eric Braeden
Role: Dr. Otto Hasslein
William Windom
Role: The President
John Randolph
Role: Committee Chairman
Harry Lauter
Role: General Winthrop
Roy Glenn
Role: Lawyer (as Roy E. Glenn Sr.)
Peter Forster
Role: Cardinal
Norman Burton
Role: Army Officer
William Woodson
Role: Naval Officer
Gene Whittington
Role: Marine Captain
Donald Elson
Role: Curator
Bill Bonds
Role: TV Newscaster
Army Archerd
Role: Referee
James Bacon
Role: General Faulkner
Ricardo Montalban
Role: Armando
John Alderman
Role: Marine Corporal (uncredited)
Alan Baxter
Role: General (uncredited)
Jack Berle
Role: Secretary of State (uncredited)
Paul Bradley
Role: Official at Briefing (uncredited)
Karl Bruck
Role: German Newscaster (uncredited)
Sam Chew Jr.
Role: Undetermined (uncredited)
Robert Cole
Role: Reporter (uncredited)
Walker Edmiston
Role: Talking Baby Chimp (uncredited) (voice)
Sig Frohlich
Role: Spectator (uncredited)
James W. Gavin
Role: Helicopter Pilot (uncredited)
George Golden
Role: Official at Briefing (uncredited)
James Gonzalez
Role: Official at Briefing (uncredited)
Joe Gray
Role: Bodyguard (uncredited)
Bob Harks
Role: Aide (uncredited)
Linda Harrison
Role: Nova (archive footage) (uncredited)
Elizabeth Harrower
Role: Reporter at Hotel (uncredited)
Shep Houghton
Role: Bystander (uncredited)
Joseph La Cava
Role: Waiter (uncredited)
Robert Nichols
Role: Reporter (uncredited)
Ron Pinkard
Role: Undetermined (uncredited)
Janos Prohaska
Role: Heloise (uncredited)
Tony Regan
Role: Reporter at Hotel (uncredited)
Stephen Roberts
Role: Gen. Brody (uncredited)
Hank Robinson
Role: Reporter (uncredited)
James B. Sikking
Role: Control Room Officer (uncredited)
Jack Slate
Role: Reporter (uncredited)
Arthur Tovey
Role: Official at Briefing (uncredited)
William Tregoe
Role: Hotel Receptionist (uncredited)
William Beckley
Role: British News Anchor (uncredited)
