According to Jimmy Neutron's teacher Ms. Fowl, Calamitous was once an intelligent classmate of her's who had the habit of not finishing things, from food to even a sentence. His inability to finish things lead him to never finishing his homework as noted by Misses Fowl which strengthens the idea he was held back. The only he could finish was a robotic suit, though he didn't consider it finished since he didn't put a bathroom into it. He later overcomes this to some extent, and Finbarr Calamitous is heard completing sentences as seen in Operation: Rescue Jet Fusion, The Great Egg Heist, and The Jimmy Timmy Power Hour 2: When Nerds Collide. However, he still has a habit of not finishing his plans, or more specifically, he is able to carry out his plans but does not plan on what he is going to do after that. He is Jimmy's arch-nemesis and the show's most recurring antagonist. 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 a tiny, near-sighted, eccentric, old genius, who is one of the most brilliant evil minds on the planet, and he would be more dangerous if he didn't have the bad habit of never finishing what he starts. Calamitous is determined to get Jimmy to finish his projects for him as he cannot finish them himself. 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. He appears in the episodes Professor Calamitous, I Presume, The Great Egg Heist, Operation: Rescue Jet Fusion, Lights! Camera! Danger!, My Big Fat Spy Wedding, The League of Villains and The Jimmy Timmy Power Hour 2: When Nerds Collide.
Calamitous appears in "Professor Calamitous, I Presume," "The Great Egg Heist," "Operation: Rescue Jet Fusion," "Lights! Camera! Danger!", "My Big Fat Spy Wedding," "Jimmy Timmy Power Hour 2: When Nerds Collide," and "The League of Villains".
Calamitous also has a robot bodyguard and disguise called the CalamiBot. He appears as quite an odd character
Dr. 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 Fairy World 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 together, 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.
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. 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. He has also been the main antagonist in Nicktoons Unite! and Nicktoons: Attack of the Toybots where he faced (beside Jimmy Neutron & Timmy Turner) Danny Phantom, SpongeBob SquarePants and other Nicktoon heroes.