Boris Karloff

James Lee Wong

Grant Withers

Police Capt. Sam Street

Maxine Jennings

Myra Ross

Evelyn Brent

Olga Petroff / Countess Dubois / Sophie Dome

George Lloyd

Devlin

Lucien Prival

Anton Mohl

John St. Polis

Carl Roemer

William Gould

Theodore Meisle

Hooper Atchley

Christian Wilk

John Hamilton

Simon Dayton

Wilbur Mack

Russell

Lee Tung Foo

Tchin

Lynton Brent

Tommy

Grace Wood

Mrs. Roemer

Frank Bruno

Lescardi (uncredited)

Ed Cassidy

Ambulance Doctor (uncredited)

Wheaton Chambers

Chemistry Lab Director (uncredited)

Clancy Cooper

Warehouse Man (uncredited)

George DeNormand

John (uncredited)

Lester Dorr

Coroner (uncredited)

Herbert Evans

Wilk's Butler (uncredited)

Dick Reinhart

Dock Worker (uncredited)

William Nigh

Director

William T. Lackey

Producer

Houston Branch

Screenplay

Russell F. Schoengarth

Editor

W.B. Eason

Assistant Director

Scott R. Dunlap

Producer

Scott R. Dunlap

Production Manager

Abe Meyer

Music Director

Karl Zint

Recording Supervision

Gordon Bau

Makeup Artist

E.R. Hickson

Technical Supervisor

Edward J. Kay

Original Music Composer

Charles J. Bigelow

Production Manager

Harry Grundstrum

Props

Hugh Wiley

Original Story

Harry Neumann

Director of Photography