Peter McCauley

as Sir Cole

as Sir Nigel

as Grandpa Robert

as Jack Ryder (3 episodes)

as Sergeant Spragg

as Magnus (1 episode)

as Robert

as Duncan

as George

as Sorcerer (1 episode)

as Bill

as Isaiah Miller

as Professor George Challenger

as Professor George Challenger (66 episodes)

as Professor Challenger

as Det. Hudson

as Culann (1 episode), as Brach (1 episode)

as Admiral McCutcheon (2 episodes)

as Henry Doak (1 episode)

as Talmadeus (1 episode)

as Commissioner (1 episode)

as Gekkus (1 episode), as Ajax (1 episode), as Odin (2 episodes)

as Higgins (1 episode), as Captain Ezra King (1 episode)

as Chad (1 episode)