- Paul Kelly
- Lt. Dan Barton / The Black Commando
- Anne Nagel
- Jean Ashley
- Trevor Bardette
- Jensen
- Rudolph Anders
- Rudi Thysson
- Clancy Cooper
- Det. Sgt. Pat Flanagan
- Gregory Gaye
- Nazi Agent Feldon
- Ludwig Donath
- Nazi Prof. Metzger
- Beal Wong
- Quito
- Eddie Parker
- Chief Henchman Berck
- Wade Boteler
- Police Chief Burns
- Charles C. Wilson
- Desk Sgt. Cullen
- Alex Callam
- Investigator Hogan [Chs.6-9,11-15]
- Robert Fiske
- Investigator Ryan
- Selmer Jackson
- Maj. Henry Barton
- Jacqueline Dalya
- Linda - Nazi HQ Radio Receptionist[Chs.1,3,5,12-15]
- Jack Gardner
- F. Wolper [Chs.1,4,8,10,11,14]
- Kenne Duncan
- Marvin [Chs.1-3,5-6]
- George Lynn
- Chief Stover [Ch.1]
- Frank Shannon
- Police Commissioner [Ch.1]
- Gus Glassmire
- Mr. Stevens [Ch.1]
- John Elliott
- Prof. Clyde [Chs.1,4]
- Jack Rice
- Fred, Jensen's Clerk [Chs.2,4]
- Sigfrid Tor
- Lt. Kurtz [Chs.3-4]
- Joseph W. Girard
- Col. Drake [Chs.3-5]
- Dick Botiller
- Hans Steufel
- Lucien Prival
- U-499 Commander [Chs.4,15]
- Rose Plumer
- Flower Woman Spy
- Lester Dorr
- Otto H. Stahl [Chs.6-8]
- Peter Leeds
- Henchman Carl Hiecke [Ch. 9]
- Kit Guard
- Henchman Corrick [Ch.10]
- Warren Jackson
- Ralph [Ch.15]
- Henry Lysing
- Code Lessons
- Roy Brent
- The Military Policeman [Ch.10]
- Stanley Brown
- Police Lab Technician
- Joe Caits
- Messenger
- Ken Carpenter
- Newscaster [Ch.6]
- Steve Clark
- Nazi Agent
- Joseph Crehan
- Police Chief Henry Burns
- Eddie Dunn
- Weather Bureau Man
- Franklyn Farnum
- Federal Agent
- Eddie Gribbon
- First Mate
- Chuck Hamilton
- Henchman
- Jack Hendricks
- Henchman
- Eddie Kane
- Coffee Shop Counterman [Ch.12]
- Frank LaRue
- Weather Bureau Man
- Tom London
- Weather Bureau Guard
- Knox Manning
- Narrator
- Ted Mapes
- Nazi Agent
- Frank McCarroll
- Military Policeman
- James Millican
- Reporter Bill [Ch.1]
- Zon Murray
- Military Policeman
- Edward Peil Sr.
- Policeman
- Lee Phelps
- Jailer [Ch.1]
- Eddie Polo
- Special Delivery Messenger [Ch.7]
- Dick Rush
- Policeman
- Lee Shumway
- Police Dispatcher [Ch.1.15]
- Tom Steele
- Federal Agent
- Bobby Stone
- Newsboy [Ch.1]
- Harry Strang
- Henchman
- Charles Sullivan
- Truck Driver [Ch.13]
- Wally West
- Policeman
- Eddie Woods
- Henchman Kurt
- Bert Young
- Henchman
