Otto Kruger as Dr. Stendahl

Vicky Lane as Paula Dupree - the Ape Woman

Amelita Ward as Ann Forrester

Phil Brown as Don Young

Jerome Cowan as Detective W.L. Harrigan

Rondo Hatton as Moloch the Brute

Eddie Acuff as Bill

Ernie Adams as Jim

Charles Wagenheim as Fred

Eddy Chandler as Motorcycle Cop

Jack Overman as Detective - George

Pat Gleason as Tom - Second Morgue Attendant (uncredited)

William Murphy as Johnny - Errand Boy (uncredited)

Bob Pepper as Policeman at Morgue (uncredited)