Anthony Quinn as Lewis 'Mountain' Rivera

Jackie Gleason as Maish Rennick

Mickey Rooney as Army

Julie Harris as Grace Miller

Stanley Adams as Perelli (as Stan Adams)

Madame Spivy as Ma Greeny

Val Avery as Young fighter's promoter

Herbie Faye as Charlie, the Bartender

Jack Dempsey as Himself

Muhammad Ali as Himself (as Cassius Clay)

Lou Gilbert as Dr. Gilbert

Michael Conrad as Ma Greeny's Thug

Rory Calhoun as Himself

Barney Ross as

Willie Pep as

Steve Belloise as Hotel Desk Clerk

Abe Simon as

Stan Ross as

J.J. Ballargeon as

Paolo Rosi as

Alex Miteff as

Gus Lesnevich as

Al Bain as Police Officer (uncredited)

William Calhoun as Self - Rivera's wrestling opponent (uncredited)

Nancy Cushman as Woman on Elevator (uncredited)

Sig Frohlich as Diner Patron (uncredited)

John Indrisano as Barfly Watching TV (uncredited)

Arthur M. Mercante as Referee (uncredited)

Angelo Rossitto as Midget Wrestler Outside Wrestling Ring (uncredited)

David Susskind as Self - Trailor Narrator (uncredited)