Evil Jimmy Neutron

Evil Jimmy is one of Jimmy's clones created in "Send in the Clones" and "The Trouble with Clones". He was created to do chores for Jimmy, though he causes trouble and escapes instead leaving the real Jimmy in trouble with his friends and the other clones iced, even though he hasn't done anything wrong. He later makes prank calls all over the Earth after hijacking the communication satellite. Not long after the prank calls he is captured by Jimmy.

Jimmy eventually attempts to turn Evil Jimmy good, though he fails, and Evil Jimmy just pretends to have redeemed himself, until he is able to use the duplication machine in order to create a whole new evil planet where everyone is a total monster like him. Unfortunately, the duplication device destroys the original of what ever it creates. The cause is revealed to be a dark chip placed in the machine, which he destroys in hopes of banishing Jimmy to the Dark Matter Dimension along with the rest of the planet. Then, Evil Jimmy and the planet start to disappear as he swears revenge shortly after. He was voiced by Rob Paulsen.

Trivia

 * Had the series continued, there would've been an episode where Evil Jimmy and his evil clones escaped from the Dark Matter Dimension and attacked Jimmy and his class, who were on a field trip to an asteroid.
 * Despite appearing in two episodes, he is without a doubt, Jimmy's worst enemy and the most evil villain to come out of the franchise and one of the most evil villains in the Nicktoons franchise alone (along with Dag, Dark Danny, Fire Lord Ozai and Fire Lord Azulon).
 * His voice is a take on Jack Nicholson.