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"Dexter's Rival"
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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
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 segment of the third episode in season one of Dexter's Laboratory. It 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 segment of the twelfth episode in the same season on December 25, 1996.

In this episode, Dexter meets Mandark, a boy in his class at school who quickly turns out to be smarter than him. After being ordered by Mandark to shut his laboratory down just so his can gain more power, Dexter enlists Dee Dee's help to get revenge on him.


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 and proves to be smarter than Dexter, which made the teachers give him 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 becoming Mandark's lackey or shutting down his lab and discontinuing any further experiments there 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 is initially reluctant to Mandark's request, but knowing 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.






  • This episode features character debuts of Mandark, Mr. Luzinsky, and Quadraplex T-3000 Computer.
  • Mandark unrequited love for Dee Dee is first shown in this episode.
  • Dexter's computer physically interacts with him for the first time by using a robotic arm to cling glasses with Dexter.
  • In the PlayStation 2 and Nintendo DS versions of the 2006 video game Cartoon Network Racing, players can watch this episode after winning a tournament as a Dexter's Laboratory representative in the first tournament.

Cultural References[]

  • Non known.

Episode Connections[]


  • This episode reveals that Mandark has the ability to read minds, but this power is never mentioned again in the series.
  • 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.
  • When Mandark holds up two of his fingers on his left hand as he says "I leave you with two choices" to Dexter, said hand suddenly gains a fifth finger.
  • 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.
  • Despite airing as part of the third episode of season one, "Dexter's Rival" was actually the first episode to be produced.