- Scott Kolk
- Agent Dexter (X-9)
- Jean Rogers
- Shara Graustark
- David Oliver
- Pidge
- Monte Blue
- Baron Michael Karsten
- Henry Brandon
- Blackstone
- Larry J. Blake
- Chief FBI Agent Wheeler
- Henry Hunter
- FBI Agent Tommy Dawson (C-5)
- George Shelley
- Henchman Packard
- Lon Chaney Jr.
- Maroni
- Si Jenks
- 'Jolly Roger' Ticket Barker [Chs. 1, 4, 7-9]
- Lynn Gilbert
- Rosel [Chs. 2, 6-7, 12]
- Robert Dalton
- Thurston
- Leonard Lord
- Ransom [Chs. 1-6]
- Ben Hewlett
- Scarlett)
- Bob Kortman
- 'Trader' Delaney [Chs. 7-9, 11-12]
- Eddie Baker
- Police Officer
- Ted Billings
- Crewman Escaping Fire
- Thomas Carr
- FBI Agent Tracy - Phoney Newsboy [Chs. 3, 5, 7, 8]
- Jack Cheatham
- Henchman Sebastian [Chs. 8, 11-12]
- George DeNormand
- Henchman
- Al Ferguson
- FBI Agent Dyer [Chs. 1, 7]
- Max Hoffman Jr.
- Henchman Marker [Chs. 1-2]
- George Magrill
- Freighter Crewman [Chs. 9-10]
- Charles Murphy
- Jolly Roger Ticket-Taker
- Eddie Parker
- Marine Guard [Ch. 1] / FBI Agent Crain [Chs. 6-8, 11-12] / Henchman [Chs. 11-12] (uncredited)
- Edward Peil Sr.
- The Fence [Chs. 11-12]
- Elliott Rothe
- Agent Jimmie Tilden [Ch. 1]
- William Royle
- FBI Agent Dunn [Chs. 1, 2, 5-7, 10, 12]
- Dick Rush
- Sheriff
- Tom Steele
- Policeman [Chs. 1-2] / Marine Guard [Ch. 1] / Henchman [Chs. 2, 5, 10] / FBI Agent [Chs. 7-8, 11] / 'Jolly Roger' Sailor [Chs. 9, 11-12] (uncredited)
- Charles Sullivan
- Truck Driver [Ch. 4]
- Eddy Waller
- Lawyer Carp [Chs. 2, 12]
