Roddy McDowall as Caesar

Don Murray as Breck

Ricardo Montalban as Armando

Hari Rhodes as MacDonald

Severn Darden as Kolp

Lou Wagner as Busboy

Natalie Trundy as Lisa

John Randolph as Commission Chairman

Asa Maynor as Mrs. Riley

Joyce Haber as Zelda

H.M. Wynant as Hoskyns

David Chow as Aldo

Buck Kartalian as Frank - Gorilla

John Dennis as Policeman

Paul Comi as 2nd Policeman

Gordon Jump as Auctioneer

Dick Spangler as Announcer

Hector Soucy as Ape With Chain

James Bacon as Ape (uncredited)

Rayford Barnes as Riot Control Commander in Plaza (uncredited)

William Bryant as Man at Auction (uncredited)

Jean Byron as Book Store Owner (uncredited)

Sam Chew Jr. as Controller (uncredited)

Francis De Sales as Auction Attendee (uncredited)

Peter Eastman as Auction Attendee (uncredited)

Erin Fleming as Cafe Customer (uncredited)

Daniel Keough as Jailguard (uncredited)

Ron Pinkard as Controller (uncredited)

Jeffrey Sayre as Restaurant Chef (uncredited)

Ruth Foster as Woman in Plaza (uncredited)