 | Arthur Kennedy | ... | Johnny Rocket, aka Kid Williams |
 | Olympe Bradna | ... | Angela Grinnelli |
 | Virginia Field | ... | Gloria Van Ness |

| Anthony Quinn | ... | Mr. Harry Trego |
 | Cliff Edwards | ... | Pinky (credits) / Sleepy |

| Cornel Wilde | ... | Tom 'Tommy' Rossi |
 | Richard Ainley | ... | Mr. George Allison |
 | William Edmunds | ... | Mr. Louis Grinnelli |
 | Frank Wilcox | ... | Denning |
 | John Ridgely | ... | Pat Martin |
 | Ben Welden | ... | Pelky |
 | Vera Lewis | ... | Mrs. Turner (scenes deleted) |
 | Charles C. Wilson | ... | Monigan (as Charles Wilson) |
 | Edwin Stanley | ... | Marion County Hospital Doctor |
| rest of cast listed alphabetically: |
 | Nat Carr | ... | (scenes deleted) |

| Herbert Anderson | ... | Reporter (uncredited) |
 | Peter Ashley | ... | Reporter (uncredited) |
 | Abie Bain | ... | Fighter (uncredited) |
 | Sidney Bracey | ... | Gloria's Butler (uncredited) |
 | George Campeau | ... | Reporter Next to Radio Announcer (uncredited) |
 | Eddy Chandler | ... | Fiske Fight Ring Announcer (uncredited) |
 | Noble 'Kid' Chissel | ... | 'Punch' Hawkins, a Fighter (uncredited) |

| David Clarke | ... | Peters, a Fighter (uncredited) |
 | Richard Clayton | ... | Messenger (uncredited) |
 | Billy Coe | ... | Billy Coe, Kent Fight Timekeeper (uncredited) |
 | Garrett Craig | ... | Reporter (uncredited) |
 | Tom Dugan | ... | Zeke, Gloria's Photographer (uncredited) |

| Frank Faylen | ... | Fighter in Locker Room (uncredited) |

| Tommy Garland | ... | Jim Fiske, a Fighter (uncredited) |
 | Sol Gorss | ... | Frank (uncredited) |

| Joe Gray | ... | Kent, a Fighter (uncredited) |
 | Creighton Hale | ... | Second Reporter (uncredited) |
 | Grace Hayle | ... | Mrs. Smithers (uncredited) |
 | Jack Herrick | ... | Fighter Sitting on Johnny's Pants (uncredited) |
 | Stuart Holmes | ... | Reporter (uncredited) |
 | William Hopper | ... | First Reporter (uncredited) |
 | J. Anthony Hughes | ... | Mr. Ben Morton (uncredited) |
 | John Indrisano | ... | Johnny Indrisano, Kent Fight Referee (uncredited) |
 | Edward Keane | ... | Indianapolis Athletic Commission Official (uncredited) |
 | John Kellogg | ... | Murphy, a Fighter (uncredited) |
 | David Kerwin | ... | East Side Pug (uncredited) |
 | Reid Kilpatrick | ... | Fiske Fight Radio Announcer (uncredited) |
 | Spike Mason | ... | Fighter (uncredited) |
 | Frank Mayo | ... | Doctor L. Madison (uncredited) |
 | Larry McGrath | ... | Al Mory, Fiske Fight Referee (uncredited) |
 | Frank Moran | ... | East Side Pug (uncredited) |
 | Jack Mower | ... | Kid Williams' Manager (uncredited) |
 | Jimmy O'Gatty | ... | East Side Pug (uncredited) |
 | Pat O'Malley | ... | Hanson Fight Ring Announcer (uncredited) |
 | Steve Pendleton | ... | Stanley, a Fighter (uncredited) |
 | Bob Perry | ... | Hanson Fight Referee (uncredited) |
 | Lee Phelps | ... | Hawkins Fight Ring Announcer (uncredited) |
 | Paul Phillips | ... | Fighter (uncredited) |
 | William 'Bill' Phillips | ... | Kovacs, a Fighter (uncredited) |
 | Jack Richardson | ... | Hanson Fight Watcher (uncredited) |
 | Frank Riggi | ... | Monk Hanson, a Fighter (uncredited) |
 | Cy Schindell | ... | Hawkins Fight Referee (uncredited) |
 | Charles Sherlock | ... | Taxi Driver (uncredited) |
 | Larry Steers | ... | Nightclub Headwaiter (uncredited) |
 | Charles Sullivan | ... | Charlie, Kid Williams' Handler (uncredited) |
 | Elliott Sullivan | ... | East Side Pug (uncredited) |
 | Leo White | ... | Hanson Fight Watcher (uncredited) |
 | Ulysses Williams | ... | Boxer (uncredited) |
 | Tom Wilson | ... | Mac, Man in Gym (uncredited) |
 | Jack Wise | ... | Nightclub Photographer (uncredited) |
There are newspaper headlines aplenty in this Bryan Foy produced programmer, but Knockout remains an above average 'B' film that will satisfy bottom of the bill fanciers. Arthur Kennedy stars as Johnny Rocket, a talented young pugilist who's got his eye on a new bride and a new job at a gym. But crafty manager Harry Trego(Anthony Quinn) soon intercedes in an effort to keep Rocket's golden gloves performing in the ring. Nicely shot by Ted McCord, the film is at its best when Rocket's life hits bottom when he gets in over his head with the smart set and wife Olympe Bradna leaves him. Bradna, a Frenchwoman, is the film's weak link, as she's unable to contain her Parisian accent whilst trying to portray the first generation daughter of a Brooklyn-based Italian immigrant. If you can overlook her shortcomings, however, you'll find this a satisfying example of the lost art of 'B' grade filmmaking.