Roddy McDowall character Cornelius
Kim Hunter character Dr. Zira
Bradford Dillman character Dr. Lewis Dixon
Natalie Trundy character Dr. Stephanie 'Stevie' Branton
Eric Braeden character Dr. Otto Hasslein
William Windom character The President
Sal Mineo character Dr. Milo
Albert Salmi character E-1
Jason Evers character E-2
John Randolph character Committee Chairman
Harry Lauter character General Winthrop
M. Emmet Walsh character Aide
Roy Glenn character Lawyer (as Roy E. Glenn Sr.)
Peter Forster character Cardinal
Norman Burton character Army Officer
William Woodson character Naval Officer
Tom Lowell character Orderly
Gene Whittington character Marine Captain
Donald Elson character Curator
Bill Bonds character TV Newscaster
Army Archerd character Referee
James Bacon character General Faulkner
Ricardo Montalban character Armando
John Alderman character Marine Corporal (uncredited)
Alan Baxter character General (uncredited)
Jack Berle character Secretary of State (uncredited)
Paul Bradley character Official at Briefing (uncredited)
Karl Bruck character German Newscaster (uncredited)
Jeff Burton character Dodge (archive footage) (uncredited)
Sam Chew Jr. character Undetermined (uncredited)
Robert Cole character Reporter (uncredited)
Walker Edmiston character Talking Baby Chimp (uncredited) (voice)
James Franciscus character Brent (archive footage) (uncredited)
Sig Frohlich character Spectator (uncredited)
James W. Gavin character Helicopter Pilot (uncredited)
George Golden character Official at Briefing (uncredited)
James Gonzalez character Official at Briefing (uncredited)
Joe Gray character Bodyguard (uncredited)
Robert Gunner character Landon (archive footage) (uncredited)
Bob Harks character Aide (uncredited)
Linda Harrison character Nova (archive footage) (uncredited)
Elizabeth Harrower character Reporter at Hotel (uncredited)
Shep Houghton character Bystander (uncredited)
Joseph La Cava character Waiter (uncredited)
Robert Nichols character Reporter (uncredited)
Ron Pinkard character Undetermined (uncredited)
Janos Prohaska character Heloise (uncredited)
Tony Regan character Reporter at Hotel (uncredited)
Stephen Roberts character Gen. Brody (uncredited)
Hank Robinson character Reporter (uncredited)
James B. Sikking character Control Room Officer (uncredited)
Jack Slate character Reporter (uncredited)
Arthur Tovey character Official at Briefing (uncredited)
William Tregoe character Hotel Receptionist (uncredited)
