Boris Karloff

Dr. Leon Kravaal

Roger Pryor

Dr. Tim Mason

Jo Ann Sayers

Nurse Judith Blair

Stanley Brown

Bob Adams

John Dilson

John Hawthorne

Hal Taliaferro

Sheriff Stanton

Byron Foulger

Dr. Bassett

Charles Trowbridge

Dr. Harvey

Ernie Adams

Pete Daggett

Minta Durfee

Frozen Therapy Patient (uncredited)

Charles Miller

Doctor Spectator Explaining Procedure (uncredited)

Eddie Dew

Doctor Spectator Listening to Explanation (uncredited)

James Conaty

Doctor Spectator (uncredited)

Wedgwood Nowell

Doctor Spectator (uncredited)

Cyril Ring

Doctor Spectator (uncredited)

Nick Grindé