- Onslow Stevens
- Stanley Stanfield
- Ada Ince
- Gloria Barnett, alias Gloria Grant
- Walter Miller
- Wade Barnett
- James Durkin
- Prof. Carl Van Dorn
- Richard Cramer
- Dorgan
- William Desmond
- Newspaper Editor MacDonald
- J. Frank Glendon
- John Cadwell
- Sidney Bracey
- Denny
- Monte Montague
- Badger
- Edmund Cobb
- Kent
- Beulah Hutton
- Sal [Chs.2,3]
- Ted Billings
- Newspaper Vendor
- Don Brodie
- Pilot
- Lee J. Cobb
- Roadwork Foreman [Chs. 3, 4]
- Frank Ellis
- Nick - Heavyset Thug [Ch. 7]
- Al Ferguson
- Stroud
- Billy Franey
- Custodian [Ch. 1]
- Lois January
- John Cadwell's Secretary
- Tom London
- Policeman [Chs. 1, 4]
- Philo McCullough
- Smuggling Gang Leader
- Jack O'Shea
- Speedboat Man [Ch. 6]
- Bud Osborne
- Speedboat Man with Binoculars [Ch. 6]
- William Steele
- Henchman
