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Dexter's Rival (Dexter's Laboratory)
Dexter's Rival.jpg
The episode that introduced us to Dexter's rival, Mandark, along with his laboratory.
Part of Season: 1
Episode Number: 3a
Air Date: May 11, 1996 (TNT)
May 12, 1996 (Cartoon Network)
December 25, 1996 (Rerun)
Director: Genndy Tartakovsky
Previous episode: Dexter's Assistant
Dexter's Debt
Next episode: Simion (Dial M for Monkey)
Old Man Dexter
Bee Where? (The Justice Friends)

"Dexter's Rival" is the first part of the third/twelfth episode in the first season of Dexter's Laboratory.


Mandark Astronomanov, a new student at Dexter's grade school, seems to be superior to Dexter academically. Mandark compels Dexter to shut down his lab so that Mandark's lab can gain more power.

Why It Rocks

  1. Watching a montage of Dexter getting ready for the first day of school at the start was pretty nice.
  2. It introduced us to Mandark, Dexter's rival who is an evil genius as much as Dexter, and him answering lots of things before the teacher asked the questions is very impressive, and his laboratory looks extremely impressive.
  3. Some emotional moments, such as Dexter crying when about to shut down his laboratory and his going to school montage becoming more dull and teachers ignoring him.
  4. Although Mandark is Dexter's rival, Dexter's plan is very clever, as he asks Dee Dee to go to Mandark's house, and she destroys his lab like she does to Dexter's (which is justified due to the reasons mentioned above).
  5. Good Ending: As mentioned above, Dee Dee comes over to Mandark's house, much to his delight and destroys his laboratory - which is justified and it ends with Dexter having some root beer in his laboratory and celebrates, along with his computer.


  • It holds a rating of 7.7/10 on IMDB.


  • This was the first Dexter's Laboratory segment to be shown twice in episodes 3 & 12 in the first season. This wouldn't be seen again until the season 3 segment, "A Mom Cartoon" in episodes 4 & 13.
  • This episode spawned the meme "I Have Failed You".