Underdog - Season 3 - Eps 13: The Marbleheads, Part 1
A strange object crash-lands on earth. A group of scientists check out the mysterious object, determining that it's a harmless, dead comet. The scientists leave the scene unaware of the fact that a secret door opens from the center of this strange thing and two evil looking space aliens emerge from this strange object.
About Underdog

Title: Underdog
First Air Date: 1964-10-03
Last Air Date: 2000-02-01
Status: Ended
Rating: 6.2/10 (from 22 votes)
Language: EN
Seasons: 4
Total Episodes: 125
Network: NBC
Genres: Animation, Comedy
Production Companies: Total Television Productions, Leonardo Productions
Synopsis
Underdog is an American animated television series that debuted October 3, 1964, on the NBC network under the primary sponsorship of General Mills, and continued in syndication until 1973, for a run of 124 episodes. Underdog, Shoeshine Boy's heroic alter-ego, appeared whenever love interest Sweet Polly Purebred was being victimized by such villains as Simon Bar Sinister or Riff Raff. Underdog nearly always speaks in rhyme, as in, "There's no need to fear, Underdog is here!" His voice was supplied by Wally Cox.
Cast

Wally Cox

Sandy Becker

Kenny Delmar

George S. Irving

Mort Marshall

Norma MacMillan

Delo States

Ben Stone

Allen Swift