Richard Dix

as John Sinclair / John Carter

Lynn Merrick

as Joan Martin Sinclair

Rhys Williams

as Ernie Sparrow

James Cardwell

as Fred (Doc) Graham

Tom Kennedy

as Ferdinand / Hammerlock

Sam Ash

as Gibson Motor Car Co. Executive (uncredited)

Egon Brecher

as Dr. Rose (replaced by Frank Reicher) (uncredited)