Dexter's Rival
Season 1, Episode 3a (12a)
Better Dexter's Rival Picture
Air date May 12, 1996 (original)
December 25, 1996 (re-airing)
Production number 101a (original)
112a (re-airing)

Dexter's Rival is the first part of the third episode of season one of Dexter's Laboratory, which first aired on May 12, 1996. It later re-aired as the first part of episode 12 in season one on December 25, 1996.

In this episode, Dexter meets Mandark Astronomonov, who quickly turns out to be better than Dexter himself.


Dexter becomes arch enemies with a new student at the school named Mandark who appears to be smarter than him and steals his title of being the smartest kid in school.


It's the first day of school and Dexter is having a great time. All of the teachers and students are welcoming him back to school because he is their star student. A new student comes along named Mandark who is so much smarter than Dexter and the teachers love him more.

Dexter is crying over himself meeting his match. Mandark comes up to Dexter and tells him that he knows that he has a lab and he wants to see it. Dexter shows Mandark is lab thinking that this is the only thing Mandark doesn't have. Mandark is unimpressed and he shows him that he has his own lab. Dexter is shocked to learn Mandark has his own, much larger, lab and seems to be his intellectual superior. Dexter is faced then with two choices, which are becoming Mandark's lackey and shutting down his lab and discontinuing any further experiments here on in.

Dexter is forced shuts down his lab and discontinue any further experiments here on in... forever. Then he miserably goes to school the next day. All of the teachers and students now ignore him and they all love Mandark the way they used to love Dexter. Just then, Dee Dee came up to Dexter yelling, "Hi Dexter!" Mandark overhears this and when he sees Dee Dee for the very first time, he falls madly in love with her. He goes up to Dexter and asks about her. Dexter is initially reluctant as his consciousnesses repeatedly demand him to refuse due to Mandark having been responsible for making Dexter miserable until one of them ends up saying that Dee Dee, as reckless and disastrous as she is, would destroy Mandark's lab, causing both Dexter and his consciousness themselves to change their minds as this would be a high opportunity for revenge. Dexter has the idea to set Dee Dee up with Mandark for a way to make him smarter.

Dexter leaves a trail of candy from Dee Dee's room to Mandark's house and Dee Dee follows it. When she gets to Mandark's house Mandark is waiting for her and he takes her into his lab. He wants to dance with her and when she hears that, she starts dancing all over the place like an idiot and she starts destroying everything in his lab. She completely destroys his entire lab and she leaves. Dexter is watching from his lab (with a root beer bottle for celebration) which he has reactivated up and continue any of his further experiments, so now he has been re-united with his one true love, which is his computer.



  • This is the first appearance of Mandark and Mr. Luzinsky.
  • This episode is where Mandark first fell in love with Dee Dee.
  • This episode shows Dexter's computer physically interacting with him for the first time, by using a robotic arm to cling glasses with Dexter.
  • This episode seems to draw animation style comparisons to the first episode of Season 1, this would indicate that this was an old episode already completed before it was aired.

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

  • The events of this episode are continued in the episode Mandarker.
  • A future episode known as Dee Dee's Rival is a spin-off version of this episode showing Dee Dee meeting Mandark's sister Lalavava.


  • This episode revealed that Mandark had the ability to read minds, however this was abandoned throughout the rest of the episode and the series.
  • One of the questions that Mandark answers is "What is the name of Neptune's moon?"; Neptune has eight moons. Mandark answers Triton which is in fact one of them.
  • Mandark says to Dexter "Some kid told me you have a laboratory." Even though Dexter's Lab is supposed to be a secret.
  • Mandark says Thomas Jefferson wrote the Bill of Rights, even though it was James Madison who did that.
  • In the episode Mandarker, Mandark said that Dexter destroyed his lab even though it was really Dee Dee who destroyed his lab.
  • This episode revealed that this is how Dexter and Mandark first met, however in the episode A Boy Named Sue, it shown that they met in a different way. This was likely a continuity error.

Production Notes

  • This episode aired twice in season 1 for an unknown reason. This would have something to do with it being linked to Mandarker which was part 2 to this episode.
  • This is the first episode when Dexter had his first day at school.


  • Although this episode is aired on May 12, 1996 in the U.S. on TBS and Cartoon Network, It was actually the first part o the first produced episode produced in the same year according to the credits, creating a continuity error in the American broadcast.
  • This episode is also aired on May 11, 1996 on TNT as a sneak preview.


  • This episode is part one of a two part episode. The part 2 being the episode Mandarker.