He is voiced by Debi Derryberry, who also voiced Jimmy Neutron.
He has the same hairstyle as his good dimensional counterpart, but has a beard and dresses up as a mad scientist.
Although proven to be Jimmy Neutron's counterpart, he does have the same interest over Cindy Vortex.
Jimmy Negatron waits for his good counterpart to finish his invention, in order to capture him and take over his world. As Jimmy Neutron finishes his machine, he teleports himself and Godard fifty years into the past, but instead find themselves locked in a cell at Negatron's lair. There, he meets his dimensional counterpart, who introduces himself. He then departs from his world as he leaves his robot, the Herminator, in charge of watching the good Jimmy. Once he arrives at the other world, he sees Cindy Vortex and fools her into drinking Black Flurp. Jimmy Neutron was able to escape by fooling Hermin into thinking that he's Negatron, who then tells him to play in the broom closet.
As Neutron tries to teleport back to his world, he finds himself in at a forest ravine. Just then, Negatron contacts him, telling him that he came prepared as he pointed out a flood behind him. As Jimmy made it out of the ravine, he later finds himself at an abandoned seaport warehouse. There, he uses a crane to help him build a submarine that took him back to Negatron's underwater evil lair. He makes it back there and uses his portal to teleport him back to his dimension.
Jimmy makes his way back to the museum and programmed Vox there. Meanwhile, Libby makes her way outside of Jimmy's lab, believing he was there and asked Vox there if she could speak to him, unaware that Negatron reprogrammed Vox, who trapped Libby in a virtual world. Jimmy Neutron arrived and teleports himself into the Virtual Reality World manages to save Libby. He then enters his lab, where he discovers that Negatron renovated it. Jimmy asks Vox if Negatron used any of his inventions. Vox informs Jimmy that Negatron used his time machine to travel back in time and change the past. Jimmy uses his time machine him and his dog, Goddard, back in time to Halloween, where they managed to find Negatron disguised as a ghost with his symbol on it.
Here are a list of evil deeds that Jimmy Negatron did to Jimmy Neutron's world.
- Kidnap Jimmy Neutron and lock him in a cell.
- Fooled Cindy Vortex into drinking black Flurp, making her fall in love with him.
- Reprogram Vox into trapping Libby in Virtual Reality.
- Used Jimmy Neutron's time machine to change the past.
- Turned Mrs. Fowl into a mummy.
- Locked Jimmy Neutron's parents in sarcophagus.
- Fooled Carl into drinking black Flurp, making him grow big.
- Mass produce black Flurp at a factory.
- Program mechanicle dinosaurs into rampaging through the streets of Retroville.
- On Halloween, he likes to wear costumes with his symbol on it.