Ralph Byrd

Greg Sanders / The Vigilante

Ramsay Ames

Betty Winslow

Lyle Talbot

George Pierce

George Offerman, Jr.

Stuff

Robert Barron

Prince Hamil

Hugh Prosser

Police Capt. Reilly

Jack Ingram

Silver / X-2

Eddie Parker

Doc / X-3

Tiny Brauer

Thorne, a.k.a. X-9 [Chs.9-11,14-15] (as Bill Brauer)