Philip 'Scotty' Grayson

Louis Hayward

Acting

Daniel F. O'Hara

Dennis O'Keefe

Acting

Dr. Anastasia 'Toni' Neva

Louise Allbritton

Acting

Dr. Ritter von Stolb

Carl Esmond

Acting

Igor Braun

Onslow Stevens

Acting

Krebs

Raymond Burr

Acting

Dr. Frederick Townsend

Art Baker

Acting

Dr. William Forrest

Lowell Gilmore

Acting

Anton Radchek

Philip Van Zandt

Acting

Dr. Homer Allen

Charles Evans

Acting

Carl Bemish

Frank Ferguson

Acting

Narrator (voice)

Reed Hadley

Acting

Police Sergeant

Ray Teal

Acting

FBI Chemist

William Tannen

Acting

Voice on Tape Recorder

Gale Storm

Acting

Mr. North

Arthur Space

Acting

Mrs. Ecko, the Landlady

Tamara Shayne

Acting

FBI Agent Miller

Keith Richards

Acting

Adolph Mizner

Grandon Rhodes

Acting

Police Detective Gaines

Steve Pendleton

Acting

Feodore

Howard Negley

Acting

FBI Agent Alison

Jimmy Lloyd

Acting

FBI Agent Thompson

Myron Healey

Acting

G.W. Hunter

John Hamilton

Acting

Paul Bryar

Acting

Fred Coby

Acting

Bert Davidson

Acting

Marten Lamont

Acting

Lee Phelps

Acting

Suzanne Ridgway

Acting

Arthur Tovey

Acting

Crane Whitley

Acting