- Warren Hull
- Mandrake the Magician
- Doris Weston
- Betty Houston
- Al Kikume
- Lothar
- Rex Downing
- Tommy Houston
- Edward Earle
- Dr. Andre Bennett
- Forbes Murray
- Professor Houston
- Kenneth MacDonald
- James Webster
- Don Beddoe
- Frank Raymond
- Dick Curtis
- Dorgan - Henchman (Chs. 6-8)
- John Tyrrell
- Dirk - Henchman
- Stanley Brown
- Green-Henchman [Chs. 1, 2, 4]
- Beatrice Curtis
- Rest Home Nurse [Chs. 3,10]
- Robert Sterling
- Henchman
- Sam Ash
- George Regan -Hypnotist [Chs. 3-5]
- Lester Dorr
- Gray - Gas Station Henchman [Chs. 8-9]
- Ernie Adams
- Henchman Brown [Chs. 2-3]
- Eddie Fetherston
- Rest Home Henchman [Chs. 10-11]
- Eddie Foster
- Ed - Blow Dart Henchman [Chs. 1-3]
- Ernie Alexander
- Cabbie
- Harry Bernard
- Construction Camp Watchman
- Stanley Blystone
- Henchman CX12
- Buel Bryant
- Rest Home & Ironworks Henchman
- Budd Buster
- Construction Camp Henchman
- George Chesebro
- Baker
- Steve Clark
- Henchman
- Charles Dorety
- Mill River Inn Henchman
- Jerry Frank
- Harper Drive Henchman
- Kit Guard
- Powerhouse Henchman
- Frank Hagney
- Harris
- Chuck Hamilton
- Bank Henchman
- Eddie Hart
- Williams
- Oscar 'Dutch' Hendrian
- Powerhouse Henchman
- Jerry Jerome
- Ward
- Eddie Laughton
- Kidnapping Henchman
- Tom London
- Mill River Inn Henchman
- Stanley Mack
- Roadster Henchman
- Knox Manning
- Narrator
- Pat McKee
- Dam Henchman
- Charles McMurphy
- Construction Foreman
- Frank Mills
- Gas Station Hitman
- Art Mix
- Ironworks Henchman
- Eddie Parker
- Henchman
- Ralph Peters
- Mohawk Steward-Henchman
- Rose Plumer
- Ship Passenger
- Cyril Ring
- Magic Mart Henchman
- Cy Schindell
- Bank Henchman
- Charles Sherlock
- Ship Henchman
- Reginald Simpson
- Parsons
- Tom Steele
- Powerhouse Henchman
- Charles Sullivan
- Henchman-Driver
- Harry Tenbrook
- Streeter
- George Turner
- Apartment-Raider
- Frank Wayne
- Henchman
- Blackie Whiteford
- Construction Camp Henchman
- Bud Wolfe
- Tower Henchman
- Bert Young
- Rest Home Henchman
