- Evalyn Knapp
- Pauline Hargrave
- Craig Reynolds
- Robert Ward
- James Durkin
- Prof. Hargrave
- John Davidson
- Dr. Bashan
- Sonny Ray
- Willie Dodge
- Frank Lackteen
- Fang
- Pat O'Malley
- Tim Sullivan - Aviator [Chs. 5-7]
- William Desmond
- Prof. Thompson [Chs. 9-12]
- Josef Swickard
- Haggins - Foreign Consul [Ch. 9]
- William Worthington
- American Consul [Ch. 1]
- Adolph Milar
- Capt. Drake [Chs. 2-3]
- James Wang
- Foo Chow - Bashan's Henchman
- Don Brodie
- Airline Official
- Wong Chung
- Chinese Man
- George DeNormand
- New York Henchman
- Beulah Hutton
- Woman Accomplice in Singapore
- Al Kikume
- Bashan's Attendant
- Ethan Laidlaw
- Fake Museum Watchman
- Tom London
- Soldier at American Consulate
- Merrill McCormick
- Guide-Henchman
- Monte Montague
- Police Guard
- Jack Mower
- Airport Inspector
- Constantine Romanoff
- Tyrone
- Churchill Ross
- American Tourist
- Dick Rush
- Cop at Fire Scene
- Philip Sleeman
- Henchman
- Charles Stevens
- Lee
- Emma Tansey
- American Tourist
- Ruth Warren
- Stewardess
