Characters played by Boris Karloff
James Lee Wong
Characters played by Grant Withers
Police Capt. Sam Street
Characters played by Maxine Jennings
Myra
Characters played by Evelyn Brent
Olga
Characters played by George Lloyd
Devlin
Characters played by Lucien Prival
Anton Mohl
Characters played by John St. Polis
Carl Roemer
Characters played by William Gould
Theodore Meisle
Characters played by Hooper Atchley
Christian Wilk
Characters played by John Hamilton
Simon Dayton
Characters played by Wilbur Mack
Russell
Characters played by Lee Tong Foo
Tchin
Characters played by Lynton Brent
Tommy
Characters played by Grace Wood
Mrs. Roemer
Characters played by Frank Bruno
Lescardi - Mohl's Henchman
Characters played by Ed Cassidy
Ambulance Doctor
Characters played by Wheaton Chambers
Chemistry Lab Director
Characters played by Clancy Cooper
Warehouse Man
Characters played by George DeNormand
John
Characters played by Lester Dorr
Coroner
Characters played by Herbert Evans
Wilk's Butler
Characters played by Dick Reinhart
Dock Worker