Evil Jimmy is one of Jimmy's clones created in the "Send in the Clones" episode. He was the last of the 6 clones created to do chores for Good Jimmy, though he was the one that was Jimmy's moral opposite and he caused trouble and tried to trick the other the clones that he's the real Jimmy, but that backfired when Jimmy iced his clones. Unfortunately, Evil Jimmy managed to escape on Jimmy's jetpack before Jimmy could stop him, leaving Good Jimmy in big trouble with his friends, despite the fact that Jimmy didn't do anything wrong.
In "The Trouble with Clones", he is revealed to have created a rocket bike which used to fly in Earth to make prank calls all over the Earth after hijacking the communication satellite. Jimmy eventually attempts to turn Evil Jimmy good, though he fails due Evil Jimmy breaking the de-evilizer, and Evil Jimmy just pretends, until he is able to use a camera known as 'The Duplicator' in order to clone the Earth, resulting in the real planet to slowly fade away. Luckily, Evil Jimmy and the real Jimmy got screened out of the cloning process (figures, Evil Jimmy doesn't want more Jimmy's around) so he took off on his rocket to reverse the effects. However when he got there, Evil Jimmy made the planet just as evil as he is thanks a Dark Matter Power Chip placed in the device. There, the environment is dark, chaotic and Jimmy's friends and parents are total monsters. Jimmy was able to confront him and reverse the process preventing the real Earth to fade into oblivion. Enraged at this, Evil Jimmy snaps the dark chip in half in an attempt to trap the real Jimmy with him on the cloned Earth in the Dark Matter Dimension before it could fade. Jimmy escaped and Evil Jimmy vowed to return.
In the planned season four premiere episode, "Deep Impacts", Evil Jimmy would've escaped from the Dark Matter Dimension along with the other evil clones and attack Jimmy and his friends, who were on a field trip to an asteroid (provided by Jimmy himself, of course), which would've led to his official defeat. Unfortunately, since DNA Productions shut down before the season could be produced, it is left up to the fans to speculate what happened to him after the series' end. It is most likely that he's still trapped in the Dark Matter Dimension or dead, though there is an extremely small chance of him escaping and wreaking havoc on anything or anyone he touches to get revenge.
- His hairstyle resembles devil horns unlike his good counterpart.
- Despite having some humorous quirks, he is without a doubt, the most evil villain to come out of the franchise.
- Evil Jimmy's voice is the same one Rob Paulsen used for the main character in The Mask animated series, which coincidentally is based on the Jim Carrey film of the same name. His catchphrase "Oh Mercy!" also references The Mask. His voice is also a take on Jack Nicholson.
- He could make his voice sound like Jimmy's, as he did in Send in the Clones to try to confuse Jimmy's other clones, but he never used this when he was passing off as him in The Trouble with Clones.
- Evil Jimmy is the only evil clone not to have the same voice actor as the original.
- It is unknown why he is not part of the League of Villains, but it was most likely because he was still trapped in the Dark Matter Dimension.