Don Taylor Director Roddy McDowall Cornelius Actor Kim Hunter Dr. Zira Actor Bradford Dillman Dr. Lewis Dixon Actor Natalie Trundy Dr. Stephanie Branton, Stevie Actor Eric Braeden Dr. Otto Hasslein Actor William Windom The President Actor Sal Mineo Dr. Milo Actor Albert Salmi E-1 Actor Jason Evers E-2 Actor John Randolph Chairman of the President's Committee of Inquiry Actor Harry Lauter General Winthrop Actor M. Emmet Walsh General Winthrop's Aide Actor Roy Glenn Lawyer Actor Peter Forster Cardinal Actor Norman Burton Army Officer Actor Bill Woodson Naval Officer Actor Tom Lowell Orderly Actor Gene Whittington Marine Captain Actor Donald Elson Curator Actor Army Archerd Referee Actor Bill Bonds TV Newscaster Actor James Bacon General Faulkner Actor Ricardo Montalban Armando Actor John Alderman Marine Corporal (uncredited) Actor Stephen Roberts General Brody (uncredited) Actor Paul Dehn Writer Frank Capra Jr. Associate Producer Arthur P. Jacobs Producer Jerry Goldsmith Original Music Joseph F. Biroc Cinematographer Marion Rothman Film Editing William J. Creber Art Director Jack Martin Smith Art Director Stuart A. Reiss Set Decoration Walter M. Scott Set Decoration Mary Babcock Hair Stylist Jack Barron Makeup Artist Daniel C. Striepeke Makeup Supervisor Francisco Day Unit Production Manager Joseph Lenzi Assistant Director Theodore Soderberg Sound Dean Vernon Sound