- Donald Woods
- Capt. Bob Dayton / John Kane
- Billy Halop
- Tim Bryant
- Robert Armstrong
- Lt. Ed Carey
- Eduardo Ciannelli
- Felix Lynx
- Kathryn Adams
- Mary Blake
- Jacqueline Dalya
- Innis Clair
- Jean Fenwick
- The Countess Irene [Ch. 4]
- Reed Hadley
- Caddens - Henchman
- Irving Mitchell
- R.S. Hinchfield
- Edgar Edwards
- Teal - Henchman [Chs. 3-6]
- John Holland
- Hess - Henchman
- Roy Gordon
- Maj. Gen. Fletcher [Chs. 1-2, 4, 11-12]
- Alex Callam
- Capt. Long [Chs. 1-2, 4, 11-12]
- Phil Warren
- Bakeman [Ch. 4]
- Bill Cody Jr.
- Jack Hurd
- Roy Barcroft
- Coast Guardsman [Ch. 12]
- Stanley Blystone
- Nevada Sheriff
- Ed Cassidy
- Denver Airport Official [Ch. 2]
- Lane Chandler
- Denver Airport Official [Ch. 2]
- Jack Rube Clifford
- Construction Crew Foreman [Ch. 5]
- Tristram Coffin
- Coast Guard Commander [Ch. 12]
- William Desmond
- Murphy - Police Officer [Ch. 9]
- Eddie Dew
- Ambulance Driver [Ch. 5]
- Amelia Earhart
- Self
- Jim Farley
- Policeman
- Al Ferguson
- Nevada Deputy [Ch. 3]
- Kenneth Harlan
- Blane [Ch. 2]
- Jerry Jerome
- Sky Raider Mechanic [Ch. 7]
- Kenner G. Kemp
- Spectator at Model Ship Trials [Ch. 2]
- Lyle Latell
- Evans - Mechanic-Henchman [Chs. 7-8]
- Pierce Lyden
- Airport Official
- Charles McMurphy
- Carter - Workman [Ch. 4]
- Bruce Mitchell
- Sheriff at Albright [Ch. 3]
- Frances Morris
- Substitute Secretary [Chs. 6-7]
- Gene O'Donnell
- Fingerprint Man [Ch. 9]
- Pat O'Malley
- Mike Casey - Motor Cop [Ch. 4]
- William Pagan
- Police Sergeant at Penthouse [Ch. 9]
- Eddie Parker
- Walker - Henchman-Driver [Chs. 3, 12]
- Jack Perrin
- Road Construction Crew Workman [Chs. 5-6]
- Stanley Price
- Curtis - Mechanic [Chs. 4, 6]
- Frank Richards
- Murdock - Henchman [Ch. 8]
- Dick Rush
- Police Captain [Ch. 9]
- Walter Sande
- Irene's Pilot-Henchman [Chs. 4-5]
- Charles Sherlock
- Sky Raider Mechanic [Chs. 2, 5]
- Tom Steele
- Car 524 Driver [Chs. 8-9]
- Larry Steers
- Army Officer [Ch. 11]
- Ken Terrell
- Henchman
- Dale Van Sickel
- Henchman [Ch. 1]
- Mary J. Woods
- Tim's Sister [Ch. 2]
