 | Liev Schreiber als Chuck Wepner |
 | Naomi Watts als Linda Wepner |
 | Elisabeth Moss als Phyllis Wepner |
 | Ron Perlman als Al Braverman |
 | Jim Gaffigan als John Stoehr |
 | Michael Rapaport als John Wepner |
 | Pooch Hall als Muhammad Ali |
 | Morgan Spector als Sylvester Stallone |
 | Jason Jones als Arty |
 | William Hill als Paddy |
 | Wass Stevens als Johnny Dicesare |
 | Kelvin Hale als Charlie Polite |
 | Megan Sikora als Flo Wepner |
| Emil Tonev als Fight Ref |
 | Georgia X. Lifsher als Rachel |
 | Catherine Corcoran als Sandy |
 | Sadie Sink als Kimberly |
| Melo Ludwig als Young Kimberly (aged 6) |
 | Georgi Georgiev als Mouthy |
| Mihail Nedyalkov als Nerk |
| Liv Rooth als Platinum Blonde |
| Joe Starr als Manny |
 | Leslie Lyles als Charlotte |
 | Velizar Binev als Referee |
 | Robert C. Kirk als Warden |
| J.J. Kandel als Jimmy the Cop |
 | Jen Ponton als Stallone's PA |
 | Rick Zahn als Police Captain |
 | Ivan Martin als Bobby Vann |
 | Jonathan Wilde als Dave |
 | Zina Wilde als Teacher |
| Charlie Meany als Sports Interviewer |
| Mark Borkowski als Joe |
| Lucinda Rogers als Lil |
 | Anthony J. Gallo als Maitre'D |
 | Shade Rupe als 16mm Cameraman (uncredited) |
| Jeff Feuerzeig | Screenplay |
| Richard Comeau | Editor |
| Jerry Stahl | Screenplay |
| Philippe Falardeau | Director |
| Liev Schreiber | Producer |
| Ashley Ingram | Casting |
| Anna Kooris | Additional Still Photographer |
| Gord Hillier | Dialogue Editor |
| Sandra O'Brien | Hairstylist |
| Nicolas Bolduc | Director of Photography |
| Jason Velez | Gaffer |
| Eddie Robison | Visual Effects Supervisor |
| Douglas Purver | Visual Effects Supervisor |
| Racquel Jenkins | Key Makeup Artist |
| Jessica Padilla | Key Makeup Artist |
| Angela Asay | Set Costumer |
| Christa Campbell | Producer |
| Kendall Anderson | Set Decoration |
| Raquel Vivve | Makeup Artist |
| Selena Arizanovic | Music Supervisor |
| Jordan Jacques Aboutboul | Set Costumer |
| Ivan Vatsov | Camera Operator |
| Jason Sax | Visual Effects Producer |
| Mathieu Berube | First Assistant Editor |
| Dora Somova | Set Costumer |
| Mihail Yanakiev | Camera Operator |
| Ryan Nowak | Sound Designer |
| Billy Hopkins | Casting |
| Sal Falcone | Hair Department Head |
| Liev Schreiber | Screenplay |
| Michael Tollin | Producer |
| Tressa Giardina | Script Supervisor |
| Lacey Hutchison | Visual Effects Coordinator |
| Christopher Raymond | Additional Camera |
| Kris Casavant | Supervising Sound Editor |
| Gino Fortebuono | Property Master |
| Sarah Dawn Hamlin | Assistant Property Master |
| Etzel Ecleston | Makeup Artist |
| Brent Poleski | Key Grip |
| Corey Allen Jackson | Music |
| Sarah Shatz | Still Photographer |
| Peter Borbely | Makeup Artist |
| Lati Grobman | Producer |
| Inbal Weinberg | Production Design |
| Gonzalo Cordoba | Art Direction |
| Michael Hauer | Steadicam Operator |
| Katelyn Mueller | Assistant Costume Designer |
| Cortney Hillman | Set Costumer |
| Angie Johnson | Makeup Department Head |
| Sylvain Bellemare | Sound Editor |
| Jerry Stein | Sound Mixer |
| Jason Maynard | VFX Artist |
| Tapio Liukkonen | Foley Artist |
| Maxwell Velazquez | Set Production Assistant |
| Carly Steyer | Production Assistant |
| Daniel Scarpati | Production Assistant |
| Anna Rybchenkov | Actor's Assistant |
| Kristina Radicheva | Assistant Production Coordinator |
| Jenny McQuaile | Production Assistant |
| Joseph Lombardi | Production Accountant |
| YeJin Joy Kim | Production Assistant |
| Jessica Jay | Production Assistant |
| Harlan Hopkins | Production Assistant |
| Coren Helene-Gitomer | Production Assistant |
| Cassie Duffy | Actor's Assistant |
| Lilia Doytchinova | Actor's Assistant |
| Leigh Dillon | Dialect Coach |
| John Buscemi | Stand In |
| Hayley Blackall | Production Assistant |
| Williams Agate III | Production Coordinator |
| Yavor Mantarkov | Cast Driver |
| Chris Forsgren | Orchestrator |
| Brittany DuBay | Music Editor |
| Janis Munz | Location Assistant |
| Paul Eskenazi | Location Manager |
| Nicolae Ilies | Digital Intermediate Colorist |
| Serge Harvey | Digital Intermediate Editor |
| Ben Spaner | First Assistant "A" Camera |
| Renato Quiridumbay | Best Boy Electrician |
| Diego Quirdumbay | Lighting Technician |
| Pavel Mitov | Gaffer |
| Nathan Lynch | Additional Second Assistant Camera |
| Anna Kooris | Still Photographer |
| Jonathon Henry | Second Assistant "A" Camera |
| Robbie Frank | Camera Loader |
| Philippe Colligan | Grip |
| DJ Carroll | First Assistant "B" Camera |
| Ilya Akiyoshi | Digital Imaging Technician |
| Robbie Frank | Assistant Camera |
| Jeff Ward | Stunt Coordinator |
| Robbie P Smith | Stunt Driver |
| Manny Siverio | Stunt Coordinator |
| Vasil Simeonov | Stunts |
| Michael Olajide Jr. | Fight Choreographer |
| Roberto Lopez | Stunts |
| Stephen Izzi | Stunts |
| Derek Serra | VFX Artist |
| John Rouse | VFX Artist |
| Jamie Gary Phillips | VFX Artist |
| Arthur Mesa | Compositor |
| Joshua Galbincea | Compositor |
| Boris Tanchev | Boom Operator |
| Max Stein | Boom Operator |
| Kostadin Saparevski | Boom Operator |
| Aaron Olson | Assistant Dialogue Editor |
| Ivaylo Natzev | Sound Engineer |
| Christopher Love | Boom Operator |
| Vladimir Kaloyanov | Sound Mixer |
| Gord Hillier | Sound Re-Recording Mixer |
| Adrian Gougov | Assistant Sound Editor |
| Patrick Christensen | ADR Mixer |
| Mimi Allard | Sound Editor |
| Nikolay Bakalov | Assistant Sound Editor |
| Chad Thuring | Props |
| Jordan Spilman | Scenic Artist |
| Vanessa Riegel | Graphic Designer |
| Dylan Pettengill | On Set Dresser |
| Brittany Henrickson | Set Decoration |
| Georgi Aleksandrov | Props |
| Mark Sussman | ADR Voice Casting |
| Aaron Schoonover | Extras Casting |
| Rita Powers | Extras Casting |
| Lindsay Padover | Extras Casting |
| Patty Connolly | ADR Voice Casting |
| Michael Cristofer | Writer |
