Don Terry

Larry Kent

Gwen Gaze

Toni Morrell

Walter Miller

Carter 'The Shark' Collins

Grant Withers

Roderick Gridley

Hobart Bosworth

Dr. X

Yakima Canutt

Dreer (Mole-Men Leader)

William Farnum

George Brennan Westmore (Editor)

Joe Caits

Saltwater Jerry [Chs.1,4-7,13-15]

Colin Campbell

Hawkins (the Butler) [Chs. 1-3]

Dave O'Brien

Det. Jameson [Chs. 4-7]

William Royle

Paul Thorndyke [Ch.1]

Warner Richmond

Capt. Tom Stanton, alias Capt. Tom Faxton [Ch.1]