Don 'Red' Barry as Mike O'Hara, "King Cobra"

Sheila Ryan as Janet 'J.L.' Brannigan

Tom Brown as Joe O'Hara

Joseph Crehan as Oscar Brannigan

John Cason as Tiger Johnson

Tony Canzoneri as Swinger Markham

Joey Adams as Duke Hensel

William Edmunds as Professor Berger

Edit Angold as Mama Berger

Margia Dean as Joy White

Harry Brown as Fight Manager

Lyle Talbot as Radio Announcer

Michael Vallon as Bettor

Sam Flint as Doctor

Frankie Van as Referee

Dan Tobey as Fight Announcer

James J. Casino as Boxer (uncredited)

Ned Roberts as Fighter (uncredited)

Jimmy Martin as Fight Second

Chester Clute as Timid Man

Jack Perry as Trainer (uncredited)

John Breen as Fight Spectoator (uncredited)

Noble 'Kid' Chissell as Fight Spectator (uncredited)

Bobby Henshaw as Fight Spectator (uncredited)

Charles Morton as Fight Spectator (uncredited)

Sol Murgi as Fight Spectator (uncredited)

Stanley Price as Fight Spectator (uncredited)

Mark Plant as Gangster

Harvey Parry as Bit Role (uncredited)

Al Bain as Fight Spectator (uncredited)