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)

Sam Chew Jr.

Character: Undetermined (uncredited)

Robert Cole

Character: Reporter (uncredited)

Walker Edmiston

Character: Talking Baby Chimp (uncredited) (voice)

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)

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)

William Beckley

Character: British News Anchor (uncredited)