Evil Jimmy is one of Jimmy's clones created in The Adventures of Jimmy Neutron: Boy Genius episode "Send in the Clones". He was the last of the six clones created to do chores for Jimmy, though he instead caused trouble and tried to trick the other the clones that he was the real Jimmy, but that backfired when Jimmy froze his clones. Unfortunately, Evil Jimmy managed to escape on Jimmy's jetpack, leaving Jimmy in big trouble with his friends.
In "The Trouble With Clones", Evil Jimmy is revealed to have created a rocket bike which he used to make prank calls all over the Earth after hijacking a communication satellite. Jimmy eventually attempts to turn Evil Jimmy good, but this fails due to Evil Jimmy breaking the de-evilizer. Evil Jimmy pretends to have reformed 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. Evil Jimmy then made the clone planet just as evil as himself thanks a Dark Matter Power Chip placed in the device. The real Jimmy was able to confront him and reverse the process, saving the real Earth from 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 theDark Matter Dimension before it could fade. Jimmy escaped and Evil Jimmy vowed to return.
In a planned episode for the unmade fourth season, "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.
- His hairstyle resembles devil horns unlike his good counterpart.
- Evil Jimmy's voice is the same one Rob Paulsen used for the main character in The Mask animated series, 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.
- Evil Jimmy is the only evil clone not to have the same voice actor as the original.