- Kane Richmond
- Alan Armstrong / Spy Smasher / Jack Armstrong
- Marguerite Chapman
- Eve Corby
- Sam Flint
- Adm. Corby
- Hans Schumm
- The Mask
- Tristram Coffin
- Drake
- Franco Corsaro
- Capt. Pierre Durand [Chs. 1-4]
- Hans von Morhart
- Capt. Gerhardt [Chs. 1, 8, 12]
- Georges Renavent
- Gov. LeComte [Ch. 3]
- Rudolph Anders
- Dungeon Col. Von Kohr [Ch. 1]
- Henry Zynda
- Ritter Lazar [Ch. 1]
- Paul Bryar
- Lawlor
- Tom London
- Crane
- Richard Bond
- Henchman Hayes
- Crane Whitley
- Hauser
- John James
- Henchman Steve
- Lowden Adams
- Maitre D', Hotel Royale [Ch. 5]
- John Alban
- Hotel Royale Patron
- Frank Alten
- Captain of Guard, Headquarters [Ch. 1]
- Roy Brent
- Hanging Party Soldier [Ch. 2]
- John Buckley
- Walker, Launch Heavy [Ch. 8]
- Yakima Canutt
- Armored Car Driver [Ch. 9]
- Tommy Coats
- Hanging Party Leader [Ch. 2]
- John Daheim
- Clayworks Thug [Ch. 10]
- Arvon Dale
- Thornton, Code Expert [Ch. 11]
- James Dale
- Henchman
- Dudley Dickerson
- Train Porter [Ch. 1]
- Martin Faust
- Blacksmith [Ch. 2]
- James Fawcett
- Thug [Ch. 1] / First Warehouse Cop [Ch. 6] (uncredited)
- Bernard Fein
- Sloan
- William Forrest
- Gerald Douglas [Ch. 12]
- Martin Garralaga
- Commandant [Ch. 2]
- Slim Gaut
- Prisoner
- Duke Green
- Lumber Heavy [Ch. 7]
- Ray Harris
- Hanging Party Soldier [Ch. 2]
- Vinton Hayworth
- Camera Shop Clerk [Ch. 6]
- Howard Hughes
- Barn Thug [Ch. 3]
- Bob Jamison
- Clayworks Thug [Ch. 10]
- Jerry Jerome
- Burns, Camera Shop Thug [Ch. 6]
- Hans Joby
- Sub-Quartermaster
- Ray Jones
- Soldier
- Eddie Juaregui
- Clayworks Thug [Ch. 10]
- Bert LeBaron
- Ed - Mechanic-Thug [Ch. 6]
- George J. Lewis
- Stuart, Warehouse Spy [Ch. 8]
- Carey Loftin
- Launch Heavy [Ch. 8]
- Walter Lowe
- Clayworks Thug [Ch. 10]
- Pat Moran
- Acme Cafe Waiter [Ch. 1]
- Jack O'Shea
- Acme Cafe Customer [Ch. 1]
- Ray Parsons
- Livingston, Collins Plant Guard [Ch. 4]
- Gil Perkins
- Sub-Valve Sailor [Chs. 3-4]
- Lee Phelps
- Jail Guard [Ch. 12]
- Charles Phillips
- Barn Thug [Ch. 3]
- Hugh Prosser
- Flight 4 Squadron Leader [Ch. 7]
- Charles Regan
- Acme Cafe Manager [Ch. 1]
- Loren Riebe
- Pipeworks Thug [Chs. 6-7]
- Buddy Roosevelt
- Lieutenant
- Cy Schindell
- Raygun Thug's Henchman [Ch. 7]
- David Sharpe
- Warehouse Sniper
- George Sherwood
- Jailer [Ch. 12]
- Cy Slocum
- Martinidad Private [Ch. 2]
- Leonard St. Leo
- Martinidad Lieutenant [Ch. 2]
- Tom Steele
- Clayworks Thug [Ch. 10]
- Robert R. Stephenson
- Sub Crewman
- Duke Taylor
- First Sentry at HQ [Ch. 1] / Fritz - Bat-Plane Pilot [Ch. 4] (uncredited)
- Ken Terrell
- Second HQ Sentry [Ch. 1] / Third Warehouse Cop [Ch. 6] / Raygun Thug [Ch. 7] (uncredited)
- Louis Tomei
- Joe, Warehouse Thug [Ch. 8]
- Sid Troy
- Gold Heavy [Ch. 9]
- Nicholas Vehr
- Whipmaster-Dungeon Guard [Ch. 1]
- Max Waizmann
- Auto Records Clerk [Ch. 6]
- Robert J. Wilke
- Chief Government Agent [Chs. 1-2, 10-11]
- Bill Wilkus
- Pipeworks Heavy [Chs. 6-7]
- Bud Wolfe
- Craig, Second Warehouse Cop [Ch. 6]
- Carleton Young
- Taylor, Barn Thug [Ch. 3] / Power Clerk (uncredited)
