According to Jimmy Neutron's teacher Ms. Fowl, Calamitous was once an intelligent student of hers who had the habit of not finishing things(this ranged from homework to inventions and to sentences which is why Ms. Fowl failed him continuously). However, after he develops his rivalry with Jimmy, he took classes and was able to finish sentences, but he sometimes couldn't get far ahead into his plans. After his first encounter with Jimmy, he was set on destroying the boy genius and his friends for good and conquer the world.
Calamitous is an old man roughly Jimmy's size, with grey bushy eyebrows and mustache, wearing a helmet that supports his glasses, wears a lab coat with blue-gray gloves, plaid pants, and black loafers.
Professor Calamitous was one of the main antagonists in "Jimmy Timmy Power Hour 2", being the main villain from Jimmy's universe while Anti-Cosmo and his minions filled the role as the villains in Timmy Turner's world. While Jimmy was searching for a date for his Friday of the 13'th school dance, Calamitous was seen in his robot suit having robbed a bank and teaming up with one of Jimmy's minor enemies. Jimmy stopped him and Calamitous returned to his mountain lair afterwards.
When he caught sight of Timmy Turner's fairy godparents Cosmo and Wanda, he planned to use their power to conquer the world. However, everyone went to Dimmsdale, which was in Timmy's world, so Calamitous followed them where his 2D form was seen for the first time. Somehow, he made his way into Fairyworld and met with Anti Cosmo who wanted to be let out in exchange for offering Calamitous power. Calamitous did as he was asked and let all the Anti Fairies out, but Anti Cosmo betrayed him and locked him in a cell with Jorgen Von Strangle.
After a while, Calamitous and Jorgen decided to work together to get out of their cell, and after a few attempts, they finally got out. They then got to Earth where the Anti Fairies proceeded to cause mischief. However, the Anti Fairies were stopped by Jimmy, Timmy, and their friends, and then locked them up in one of Jimmy's inventions, and Calamitous and Jorgen were rushing to the cube, but a ray by a gene-splicer used by Timmy borrowed from his friend A.J. resulting in Calamitous and Jorgen merging, but the only difference was Calamitous' head being on Jorgen's right shoulder.
Calamitous, having the superior brain power, took control of Jorgen's body and attempted to destroy Jimmy and Timmy, but they were turned to snails instead, as Da Rules prevent any murder by magic. Despite this, Calamitous/Jorgen captured Cindy Vortex and took her to Retroville where Calamitous proceeds to use his new powers to cause havoc. Jimmy, Timmy, and their friends return to Retroville where Calamitous has turned Cindy into a goldfish and has created a giant bomb that can destroy the entire world.
Later the Jimmy, Timmy, and their remaining friends try to free Cindy and stop the bomb, however Calamitous soon sees Jimmy and Timmy and is confused on how they are still alive. Jorgen tells Calamitous that he can't use magic to kill anyone as it's against Da Rules. Calamitous yells at Jorgen to kill one of his enemies, but Jorgen refuses again. Timmy realizes that Jorgen hates seeing people breaking Da Rules and decides this might help them
The two teammates developed a plan to stop Calamitous, where they were doing things that were breaking Da Rules such as riding giant floating hot dogs or having Carl marry a turkey or have Cosmo use magic to win rock, paper, scissors. All of this rule-breaking caused Jorgen to regain control of his body, where Jimmy then uses the gene-splicer to separate them. Jorgen dismantled the bomb and shrunk Calamitous into a bottle where he was kept by Carl Wheezer. However, during the interdimensional Friday the 13'th dance, Carl asked Wanda to turn Calamitous into Judy Neutron much to Wanda's dismay.