Insp. David Worth
Laura Keith
Spade Gordon
Nila
Agent Steve Evans
Prof. Paul Williams [Chs. 1-6]
Prof. James Clayton [Chs. 1, 10-12]
Frank Chambers [Ch. 8]
Grey - Henchman [Chs. 1-3] / Haskell - Pilot [Chs. 4-5] / Larkin - Henchman [Chs. 7-8] / Native #1[Ch. 11-12]
Mac - Henchman / False Prof. Graves [Chs. 6-7] / Cave Guard #1[Ch. 11]
Ali [Chs. 1, 10-12]
Det. O'Hara [Ch. 9]
Zod - Pursuit Plane Pilot [Chs. 10] (as Bob Wilke)
Native #3 [Ch. 11]
Porter [Ch. 9]
Prof. Elwood M. Graves [Ch. 6] (uncredited)
Cave Guard #2 [Ch.11] (uncredited)
Native #2 [Chs. 11-12] (uncredited)
Courier (uncredited)
Digger #1 [Chs. 1, 11-12] (uncredited)
Warehouse Thug [Chs. 1-2, 10] (uncredited)
Ambulance Thug [Ch. 3] (uncredited)
Headquarters Thug [Ch. 9] (uncredited)
Digger #2 [Chs. 1, 11-12] (uncredited)
Native #4 [Ch. 11] (uncredited)
Roadblock Thug [Ch. 5] / 6th Native [Ch. 11] (uncredited)
Museum Thug [Ch. 6] (uncredited)
Chemical Company Thug [Ch. 4] (uncredited)
Roadblock Thug [Ch. 5] / Native 5 [Ch. 11] (uncredited)