Dexter's Laboratory (1996–2003)
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Dexter's Rival/Dial M for Monkey: Simion/Old Man Dexter 

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In "Dexter's Rival", Dexter clearly shows disdain for a new kid in school, who has a lab just like his, albeit a bigger and more superior one. In "Simion", the result of an failed ... See full summary »


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Episode cast overview:
Dexter (voice)
Allison Moore ...
Dee Dee (voice)
Mandark (voice)
Teacher #2 / Principal / Robot / Monkey / Captain (voice)
Dad / TV Announcer / Old Man Dexter (voice)
Mom / Teacher #1 / Computer / Worm (voice)
Main Title Narrator (voice)
Simion (voice)
Robert Ridgely ...
Commander (voice) (as Bob Ridgley)
Paula Tiso ...
Honeydew (voice)


In "Dexter's Rival", Dexter clearly shows disdain for a new kid in school, who has a lab just like his, albeit a bigger and more superior one. In "Simion", the result of an failed experiment vows revenge against the humans that did it. In "Old Man Dexter", Dexter makes himself older so he can stay up later. Written by Anonymous

Plot Summary | Add Synopsis



Release Date:

12 May 1996 (USA)  »

Company Credits

Production Co:

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Did You Know?


In a quiz session, Mandark says that Thomas Jefferson wrote the Bill of Rights. Jefferson was serving as U.S. Ambassador to France at the time. George Mason wrote the Bill of Rights. See more »


Mandark: Please, sir, call me... MANDARK!
See more »


References Santa Claus Conquers the Martians (1964) See more »

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User Reviews

Simion/Old Man Dexter
24 October 2015 | by (India) – See all my reviews

Dexter's Laboratory (commonly abbreviated as Dexter's Lab) is an American comic science fiction animated television series created by Genndy Tartakovsky for Cartoon Network, and the first of the network's Cartoon Cartoons. The series follows Dexter, a boy-genius and inventor with a secret laboratory, who constantly battles his sister Dee Dee in an attempt to keep her out of the lab. He also engages in a bitter rivalry with his neighbor and fellow-genius Mandark. The first two seasons contained additional segments: Dial M for Monkey, which focuses on Dexter's pet lab-monkey/superhero, and The Justice Friends, about a trio of superheroes who share an apartment.

Dexter's Laboratory received high ratings and became one of Cartoon Network's most popular and successful original series. During its run, the series won three Annie Awards, with nominations for four Primetime Emmy Awards, four Golden Reel Awards, and nine additional Annie Awards. The series is notable for helping launch the careers of several cartoonists, such as Craig McCracken, Seth MacFarlane, Butch Hartman, and Rob Renzetti. Spin-off media include comic books, DVD and VHS releases, music albums, collectible toys, and video games.

Dexter's Rival: A new student named Mandark Astronomonov enrolls at Dexter's school and quickly turns out to be better than Dexter academically. Eventually, he even forces him to shut down his lab so that his lab (which is much bigger than Dexter's lab) can gain more power. A hurt Dexter then teams up with Dee Dee to take revenge on Mandark.

Simion: Monkey encounters an intelligent anthropomorphic chimpanzee named Simion (Maurice LaMarche), who plans to take revenge on humans for turning him into his current state.

Old Man Dexter: After Dexter is banned from watching The Late Early Movie due to his age, he decides to accelerate his age so that he can see the movie, but Dee Dee tampers with the age acceleration process, causing him to turn into a 95-year-old man.

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