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"Dexter's Rival"
"Dial M for Monkey: Simion" Dial M for Monkey: Simion
Dexter's Rival
Season 1, Episode 3a
Episode name reference to/pun on: None
Better Dexter's Rival Picture.png
Air date May 11, 1996 (TNT)
May 12, 1996 (original)
Production number 101a (original)
112a (rerun)
Storyboard by Genndy Tartakovsky
Directed by Genndy Tartakovsky
Todd Fredericksen (background design)
Martin Ansolabehere (background color stylist)

Dexter's Rival is the first part of the third episode of season one of Dexter's Laboratory, which first aired on TNT on May 11, 1996, and on both TBS and Cartoon Network on May 12, 1996. It later re-aired as the first part of episode 12 in season one on December 25, 1996. In the episode, Dexter becomes arch enemies with a new student at school named Mandark, who appears to be smarter than him and steals his title of being the smartest kid in school.

This episode is often referred to as episode 3 because it was the third episode to air on TV, and "DeeDeemensional" was the first episode that aired on TV. However, this episode was the first to be produced.


On Dexter's first day of school for the new year, his teachers and students welcome him back as their star pupil. A new student named Mandark comes along, who proves to be smarter than Dexter, and the teachers give him more praise.

After school, Dexter cries over meeting his match. Mandark confronts Dexter and tells him that some kid told him that Dexter has a laboratory. Dexter shows Mandark his lab thinking that this is the only thing Mandark does not have. Mandark, unimpressed by Dexter's laboratory, shows Dexter his own lab. Dexter is shocked to learn that Mandark's lab is much larger, and Mandark seems to be his intellectual superior. Dexter is then faced with two choices, which are either becoming Mandark's lackey or shutting down his lab and discontinuing any further experiments here on in.

Dexter chooses to shut down his lab and discontinue any further experiments forever. He miserably goes to school the next day, where his teachers and fellow students now shun him and praise Mandark the way they used to love Dexter. Dee Dee comes up to Dexter and yells, "Hi Dexter!" When Mandark overhears this, he falls in love with Dee Dee for the very first time. He confronts Dexter to request a date with her. Dexter, initially reluctant to Mandark's request, says that Dee Dee, as reckless and disastrous as she is, would destroy Mandark's lab, changes his mind as this would mean a perfect opportunity for revenge. Dexter whispers to Mandark how to get Dee Dee to his house.

Dexter leaves a trail of candy from Dee Dee's room to Mandark's house, and Dee Dee follows it. When she arrives at Mandark's house, he awaits her and takes her into his lab. He wants to dance with her, but she clumsily dances all over his lab and destroys everything in it in the process. Dexter watches from his lab (with a root beer bottle for celebration), which he has reactivated to continue his further experiments. He is now reunited with his one true love, his computer.






Cultural References

  • Mr. Luzinsky asked what the name of Neptune's moon was and Mandark said Triton.
  • Mr. Luzinsky asked who signed the Bill of Rights.
  • Mr. Luzinsky asked an unfinished question about an isosceles triangle
  • The unasked answers of Mandark in this episode are:
    • Dasyurid- Species of mouse-sized marsupials found in Australia and New Guinea
    • Medulla oblongata- The lower half of the brain stem

Episode Connections


  • This episode reveals that Mandark has the ability to read minds, but this power is never mentioned again in the series.
  • One question Mandark answers is "What is the name of Neptune's moon?"; Neptune has eight moons. Mandark's answer, Triton, is one of them.
  • Mandark says to Dexter "Some kid told me you have a laboratory," even though Dexter's lab is a secret.
  • Mandark answers Thomas Jefferson as to whom wrote the Bill of Rights, but it was really James Madison.
  • In the episode "Mandarker", Mandark says that Dexter destroyed his lab even though Dee Dee actually destroyed his lab.
  • Continuity: This episode reveals how Dexter and Mandark first met; however, "A Boy Named Sue" shows that they met differently.

Production Notes

  • This episode aired twice in season 1. This would have something to do with it being linked to "Mandarker", a continuation of this episode. The second airing of this episode is not included with the episodes "Bee Where" and "Mandarker" in Disc 2 of the Season 1 DVD release due to the first airing already being on Disc 1.
  • This is the first episode to show Dexter's first day at school.
  • Production on this episode began long before the series premiered.
  • As mentioned above, this episode is meant to be the series premiere, but "DeeDeemensional" aired first, as mentioned above. This episode was held off until the following week as the first part of the third episode.
  • This episode draws animation style comparisons to the first episode of Season 1, which would indicate that this was an old episode already completed before it was aired.


  • Though it first aired on May 12, 1996, in the U.S. on TBS and Cartoon Network, it was actually the first part of the first produced episode produced in the same year according to the credits, creating a continuity error in the American broadcast.
  • This episode aired on May 11, 1996, on TNT as a sneak preview.
  • Intended to be the first episode to air because it was produced first, Cartoon Network, which often airs episodes out of production order, aired it third.