Dr. Horatio Beaker / Mitch the Monkey / Morse Operator (voice)

Doctor Venus (voice)

Colonel Steve Zodiac (voice)

Robert the Robot (voice) (uncredited)

Commander Wilbur Zero / Kazak (voice)

Mike Mercury / Jason Munroe III (voice)

Professor Rudolph Popkiss / Black Morgan (voice)

Sheriff Tex Tucker / Telegraph Operator Dan Morse (voice)

Dusty the Dog / Rocky the Horse / Foreman (voice)

Martha 'Ma' Jones (voice)

Sheriff Tex Tucker (singing voice) (uncredited)