The Mad Monster

George Zucco

Lorenzo Cameron

Anne Nagel

Lenora Cameron

Johnny Downs

Tom Gregory

Glenn Strange

Petro

Robert Strange

Professor Blaine

Gordon De Main

Professor Fitzgerald

John Elliott

Professor Hatfield

Reginald Barlow

Professor Warwick

Sarah Padden

Grandmother

Mae Busch

Susan

Ed Cassidy

Father

Henry Hall

Country Doctor

Eddie Holden

Jed Harper