Liev Schreiber as Chuck Wepner

Naomi Watts as Linda Wepner

Elisabeth Moss as Phyllis Wepner

Ron Perlman as Al Braverman

Jim Gaffigan as John Stoehr

Michael Rapaport as John Wepner

Pooch Hall as Muhammad Ali

Morgan Spector as Sylvester Stallone

Jason Jones as Arty

William Hill as Paddy

Wass Stevens as Johnny Dicesare

Kelvin Hale as Charlie Polite

Megan Sikora as Flo Wepner

Emil Tonev as Fight Ref

Georgia X. Lifsher as Rachel

Catherine Corcoran as Sandy

Sadie Sink as Kimberly

Melo Ludwig as Young Kimberly (aged 6)

Georgi Georgiev as Mouthy

Mihail Nedyalkov as Nerk

Liv Rooth as Platinum Blonde

Joe Starr as Manny

Leslie Lyles as Charlotte

Velizar Binev as Referee

Robert C. Kirk as Warden

J.J. Kandel as Jimmy the Cop

Jen Ponton as Stallone's PA

Rick Zahn as Police Captain

Ivan Martin as Bobby Vann

Jonathan Wilde as Dave

Zina Wilde as Teacher

Charlie Meany as Sports Interviewer

Mark Borkowski as Joe

Lucinda Rogers as Lil

Anthony J. Gallo as Maitre'D

Shade Rupe as 16mm Cameraman (uncredited)

Leonard Zimmerman as Hotel Valet (uncredited)