James Isaac "Jimmy" Neutron is the title character and main protagonist of the film Jimmy Neutron: Boy Genius and the spin-off TV series The Adventures of Jimmy Neutron: Boy Genius. He lives with his pet robot, Goddard, and his parents, Hugh and Judy Neutron in Retroville. Jimmy appears as a typical boy who also happens to be a genius. He creates gadgets to improve his everyday life. The inventions often go awry and create hilarious trouble. The Jimmy Neutron show had its world premiere on July 20, 2002 and ended on November 25, 2006.
Jimmy's mother only calls him by his full name. His father calls him "Jimbo" and Cindy Vortex (who secretly loves Jimmy) usually calls him "Nerdtron", "Spewtron", "King Cranium", and other names. He has two best friends, Carl Wheezer and Sheen Estevez.
One of his most captivating features is the fact that his cranium projects farther than normal which is to hold his large brain.
He is the world's smartest 11-year-old boy, possessing an IQ of 210; however, he is not always very smart. Whenever his own inventions seem to gone horribly wrong and cause more destruction than anything, it is usually up to him and his friends to stop them. He was named after scientists Sir. Isaac Newton and James Chadwick. He was nicknamed "Jimmy Neutron" because of his discovery of the neutron. His birthday is March 14 (Pi Day), according to www.savejimmyneutron.com . He lives in Retroville with his robot dog, Goddard, who is named after Robert H. Goddard (a pioneer in modern rocketry) and his parents, Hugh Neutron, a bumbling car salesman and duck-lover, and Judy Neutron, a 50s style housewife. He has a photographic memory and appears to be able to read extremely fast.
Jimmy has a disproportionately large head (which is needed to house his large brain), blue eyes, and brown ice cream-shaped hair. He is often teased because he is shorter than most boys of his age. Jimmy's wardrobe consists almost exclusively of red T-shirts that sport his trademark symbol of electrons, circling a nucleus. This adds significant power to his already enormous brain. He also wears blue jeans and a pair of grey and white Converse Chuck Taylor All-Stars. His underwear consists of plaid boxer shorts as shown in the movie and in the first episode of the series, He wears knee socks. In the movie, Jimmy wore blue shorts and brown shoes. He also wears his blue lab coat (and sometimes his welding mask).
In a number of episodes, his classmates are annoyed and angered because Jimmy's brilliance renders trying to win projects and competitions things pointless (in fact Jimmy has been banned for life from the science fair to give normal kids an actual chance). This brain, a source of constant comment, allows him to invent devices that accomplish even the impossible. That might seem like a gift to most people, but to Jimmy Neutron, it often causes him trouble. He designs his wild inventions to help him deal with bothersome chores, however the inventions tend to have a flaw (usually caused by an obvious oversight) which result in a catastrophe which only he can solve. He's rarely ever thanked however as people usually know he's the cause of the problem in the first place. 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. 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 movie, he does not say "Think, think, think" or "Brain Blast!" out loud, but says them in his mind. But in the 3rd season, he seems to stop Brain Blasting and comes up with ideas right away, with the exception being Fundemonium.
Jimmy has a sweet personality, although sometimes he can be a bit arrogant. Jimmy is shown to be quite irritable around most people, the exception being his friends. He can be friendly at times, that he needs (or wants to be), but can come off as a smart aleck or nerd occasionally. He enjoys playing the hero, often taking a staunch stand against anyone he believes to be evil. He won’t back down from his beliefs as he strongly believes in himself. Jimmy is quite charming when he least tries to be, such as at the party, that he throws at his parents' absence in an early episode. He cares for his friends, family and Retroville.
However, he does have a few weaknesses; one of them is his poor communication skills. It takes him hours to explain things the "Science way" and people find his explanations hard to understand and would ask for a shorter version of his story instead. Cindy calls him silver-tongued (in a sarcastic way), in the episode "Love Potion 976/J" as he finds it, which is accessible to him only, by means of a DNA scan.
Jimmy's inventions include Goddard, a time machine, and the Nanobots. He has several gum and candy-based inventions, which include The Neutronic Air Gum, that allow humans to breathe under water, gum that allows one to memorize books, and candy, that satisfies all the tongue's taste buds. After eating such candy, humans develop a physiological need (addiction) for it. He also made inventions to help him with transportation, the most frequently employed being his flying rocket or hovercar. He also has a game pyramid, which allows players to go inside their favorite video game, and a cloning machine.
In the video games, he makes several inventions, similar to the series. Many times, he creates different types of advanced spaceships with spacebuses, spacebikes, being able to use amusement rides to create some, and finishing with his favorite, the hovercar, which he uses almost frequently. He creates these inventions in an extensive lab, located under his clubhouse, which is accessible to him only, by means of a DNA scan.
The llama-obsessed Carl Wheezer and Ultralord-obsessed Sheen Estevez are Jimmy's best friends. They may not be as smart as Jimmy, but they are very loyal to him. They are willing to help Jimmy as much as possible. Normally, these two unlikely heroes play the foils to Jimmy's genius, and sometimes solve the episode's crisis with some innocent or insane observation. Other times, they merely cause the problem. They accompany him in his wild adventures and end up in trouble. Jimmy’s friends also include Libby Folfax and Cindy Vortex. They constantly tease Jimmy for having a large head and for getting himself and the town into trouble. However, these girls get to join in Jimmy's adventures and help him save the day.
Cindy and Jimmy constantly fight with one another, and consider themselves as "rivals", but eventually, they grow to love each other, leading to a love/hate relationship. In due course, it seems that they fight to hide their true feelings. It is hard to say who really motivates the relationship, but from what we can see, it is Cindy who gives it a little push and Jimmy is quick to respond to these hints of affection. Their relationship develops further in season 3, and in the final episode Lady Sings the News, Jimmy finally kisses Cindy.
Whenever he has an idea, he will shout "Brain Blast!" where after there will be a short clip that shows Jimmy's brain. If he is willing to get out of any sticky situation, he will say "Gotta Blast!"