Boris Karloff as Prof. Nathaniel Billings

Peter Lorre as Dr. Arthur Lorentz

Maxie Rosenbloom as Maxie

Jeff Donnell as Winnie Slade

Larry Parks as Bill Layden

Maude Eburne as Amelia Jones

Don Beddoe as J. Gilbert Brampton

George McKay as Ebenezer

Eddie Laughton as Mr. Johnson

Frank Puglia as Silvio Baciagalupi

Frank Mitchell as Officer Fred

James C. Morton as Trooper Quincy

Frank Sully as Officer Joe Starrett

Patrick McVey as Munitions Plant Road Guard

Robert Emmett Keane as Alarm Clock Salesman