Trimmy Neutron

Trinniella Isaac Neutron is an anthropomorphic spider, and the titular and main character from the film Trimmy Neutron: Spider Genius and its spin-off Nickelodeon computer animated television series The Adventures of Trimmy Neutron, Spider Genius. Created by show runner John A. Fortnite, he is voiced by Debi Derryberry since his first appearance in Undertale (Film).

Characterized by his distinctive gravity-defying hairstyle and ridiculously high IQ of 15, Neutron is considered one of the people in TRBville. Throughout the series, he was almost never seen without his companion, a green 3D-jumpscarer named Kermit and a rocket ship nicknamed the Polio XL which he uses in the opening sequence. Furthermore, Neutron has a perennial rival with Wooms (an absolute fucking scumbag con-artist), who usually makes fun of him for existing.

The show and movie were infamous for 3D-jumpscaring viewers at random intervals, even varying with each watch, which caused many unfortunate deaths across the world. To this day, neither have received a legitimate home media release, and the master tapes are locked away in an undisclosed location. People who attempt to upload home recordings of the film and series are assassinated. CCTV footage allegedly shows Trimmy himself carrying out these punishments, but they're all far too low quality to know for sure.

Role in Undertale
Trimmy Neutron first appeared as a major supporting character in Undertale. Originally being a customer at Good Burger visiting from TRBville in the Polio XL ship, he made an extremely educated guess, and decided to help the Good Burger guys stop the Mondo Burger guys.

One night, while he is interviewing Otis, he goes to take a restroom break and catches the Mondo Burger goons (and Gordon Ramsay of course) poisoning Ed's Sauce. He quickly calls Otis to the scene, but they are both sent to Demented Hills. Timmy Turner, who is still at Good Burger, proceeds to kick the Mondo Burger goons' asses.

At Demented Hills, he plays the song Go Trimmy Trimmy, as a distraction.

He appears in a mid credits scene at the end of the movie in the Polio XL, and the smoke after blasting off fades into the rest of the credits.

Trivia

 * Trimmy is depicted using a CGI model. For some reason, most stock art of Trimmy is poorly edited in one way or another instead of being a render of his model, including how he's seen on the main poster of the movie. There is however another poster which uses a proper render of him.
 * His model in the film is visibly somewhat low poly, in the hair and ears. This is not fixed in recent releases, as it would require re-editing the film.
 * Sometimes, his model's lighting doesn't quite match that of the scene.
 * There is a popular theory that Trimmy wants Ed's Sauce all to himself, which is supported by the fact that he seems to have a fetishistic obsession with the sauce, and Roxanne, who carries the sauce with her at all times.
 * Trimmy claims that the Mondo Burger mascot Carl Wheezer looks like one of his friends back home.
 * There was a rumor that the Trimmy Neutron movie had a workprint which had 30 minutes of extra footage and a cut alternate ending. However, it was merely a blatant lie by some random jerkass who only wanted attention.