Jimmy is shown to be quite irritable and impatient around most people, mostly his friends and sometimes treats them like underlings. Jimmy is a nice guy, although sometimes he can be arrogant, selfish, irresponsible and a know-it-all. In the third season, he seems to stop brain blasting and comes up with ideas right away, with the exception being 'Fundemonium'. In the movie, he does not say 'Think, think, think!' or 'Brain Blast!' out loud, but says them in his mind. Jimmy will then shout, 'Brain Blast!', and arrive at the solution for whatever danger he has landed himself, his friends, or his town in. In the moment of crisis, he will urge his brain by saying, 'Think, think, think!', where upon viewer enters Jimmy's ear and goes into his brain to observe its inner workings as well, as to relive a scene from the early part of the episode. He's rarely ever thanked however as people usually know the problem was his fault in the first place and is highly considered a menace by everyone. He designs his wild inventions to help him deal with bothersome chores, play tricks on people and gets very curious when there's something unusual happening, however the inventions tend to have a flaw (usually caused by an obvious oversight) and his curiosity can take over him, which results in a catastrophe which only he can solve. That might seem like a gift to most people, but to Jimmy, it often causes him trouble. His brain, a source of constant comment, allows him to invent devices that accomplish even the impossible. In fact, Jimmy has been banned from the science fair for life to give normal kids an actual chance. In a number of episodes, his classmates are annoyed and angered because Jimmy's brilliance renders trying to win science projects and competitions things pointless. He specializes in many sciences such as quantum physics, chemistry, biology, mathematics, robotics, engineering, and astronomy. of 210, making him the smartest Retroville citizen and quite possibly the smartest individual in the whole world. A picture of him in this outfit can be seen several times in the show. In the pilot, he wore a striped shirt, brown shoes and blue shorts. He also wears a blue lab coat (and sometimes his welding mask while working on his inventions).

In the shorts and the film, Jimmy wore violet-blue shorts and brown shoes. His underwear consists of plaid boxer shorts, as shown in the film and in the first episode of the series, he wears knee socks. He also wears blue jeans and a pair of grey and white sneakers. Jimmy's wardrobe consists almost exclusively of red T-shirts that sport his trademark symbol of electrons, circling a nucleus. He is often teased because he is shorter than most of the kids his age and the youngest student in his class. Jimmy has a large forehead (which appears to be larger, due to his hair), blue eyes, and a large brown cowlick hairstyle. He is voiced by Debi Derryberry, who also voiced Coco Bandicoot, Pac-Man in Street Fighter X Tekken, Runt, Jay-Jay the Jet Plane, and Zatch Bell. Jimmy also hates being short and usually gets mad when he's reminded of it. He also loves having adventures with his best friends Carl, Sheen, Nick, Cindy, Libby, and Goddard and fighting Villains. He has an IQ of 210, making him the most intelligent resident of Retroville. Goddard (a pioneer in modern rocketry) and his parents, Hugh, a bumbling, goofy car salesman and duck-lover, and Judy who is his mother. He lives in Retroville with his robot dog, Goddard, who is named after Robert H. Jimmy is a genius inventor, but most of his inventions seem to cause more destruction than anything and it is usually up to him and his friends to stop them.

Isaac Newton, and James Chadwick who was nicknamed 'Jimmy Neutron', because of his discovery of the neutron. James Isaac 'Jimmy' Neutron (born March 14th) is the titular protagonist of the animated Nickelodeon franchise of the same name. ~ Jimmy Neutron whilst fighting the Yolkians. You steal my parents, you threaten my dog, you attack my friends and you made fun of my size.

Jimmy neutron characters