 Anthony QuinnLewis 'Mountain' Rivera | Lewis 'Mountain' Rivera |
 Jackie GleasonMaish Rennick | Maish Rennick |
 Mickey RooneyArmy | Army |
 Julie HarrisGrace Miller | Grace Miller |
 Stanley AdamsPerelli (as Stan Adams) | Perelli (as Stan Adams) |
 Madame SpivyMa Greeny | Ma Greeny |
 Val AveryYoung fighter's promoter | Young fighter's promoter |
 Herbie FayeCharlie, the Bartender | Charlie, the Bartender |
 Jack DempseyHimself | Himself |
 Muhammad AliHimself (as Cassius Clay) | Himself (as Cassius Clay) |
 Lou GilbertDr. Gilbert | Dr. Gilbert |
 Michael ConradMa Greeny's Thug | Ma Greeny's Thug |
 Rory CalhounHimself | Himself |
| BBarney RossNot listed | Not listed |
| WWillie PepNot listed | Not listed |
| SSteve BelloiseHotel Desk Clerk | Hotel Desk Clerk |
| AAbe SimonNot listed | Not listed |
| SStan RossNot listed | Not listed |
| JJ.J. BallargeonNot listed | Not listed |
 Paolo RosiNot listed | Not listed |
| AAlex MiteffNot listed | Not listed |
| GGus LesnevichNot listed | Not listed |
 Al BainPolice Officer (uncredited) | Police Officer (uncredited) |
| WWilliam CalhounSelf - Rivera's wrestling opponent (uncredited) | Self - Rivera's wrestling opponent (uncredited) |
| NNancy CushmanWoman on Elevator (uncredited) | Woman on Elevator (uncredited) |
| SSig FrohlichDiner Patron (uncredited) | Diner Patron (uncredited) |
| JJohn IndrisanoBarfly Watching TV (uncredited) | Barfly Watching TV (uncredited) |
| AArthur M. MercanteReferee (uncredited) | Referee (uncredited) |
 Angelo RossittoMidget Wrestler Outside Wrestling Ring (uncredited) | Midget Wrestler Outside Wrestling Ring (uncredited) |
 David SusskindSelf - Trailor Narrator (uncredited) | Self - Trailor Narrator (uncredited) |
