Larry Kent
Don Terry
Toni Morrell
Gwen Gaze
Saltwater Jerry [Chs.1,4-7,13-15]
Joe Caits
Hawkins (the Butler) [Chs. 1-3]
Colin Campbell
Det. Jameson [Chs. 4-7]
Dave O'Brien
Paul Thorndyke [Ch.1]
William Royle
Capt. Tom Stanton, alias Capt. Tom Faxton [Ch.1]
Warner Richmond
Carter 'The Shark' Collins
Walter Miller
Capt. Samuel Cuttle
George Rosener
Roderick Gridley
Grant Withers
Dr. X
Hobart Bosworth
Nurse Zanya
Sandra Karina
Prof. Gault
P.J. Kelly
Dreer (Mole-Men Leader)
Yakima Canutt
George Brennan Westmore (Editor)
William Farnum
Director
Elmer Clifton
Screenplay
Story
L. Ron Hubbard
George M. Merrick