as Larry Kent
as Toni Morrell
as Carter 'The Shark' Collins
as Capt. Samuel Cuttle
as Roderick Gridley
as Dr. X
as Nurse Zanya
as Prof. Gault
as Dreer (Mole-Men Leader)
as George Brennan Westmore (Editor)
as Saltwater Jerry [Chs.1,4-7,13-15]
as Hawkins (the Butler) [Chs. 1-3]
as Det. Jameson [Chs. 4-7]
as Paul Thorndyke [Ch.1]
as Capt. Tom Stanton, alias Capt. Tom Faxton [Ch.1]