This is a list of the fictional characters that appear on the manga, anime and live-action series, Great Teacher Onizuka (GTO, for short).
A 22-year-old, blonde-haired biker, virgin, and former bōsōzoku, Eikichi Onizuka is the protagonist of GTO. He graduated from a bottom-rung university by cheating and, as such, cannot get a decent job. His primary way of spending time is peeping up girls' skirts at a local mall. He is very athletic and has a second dan black belt in karate.
Onizuka decides to become a teacher. His initial training is in the Musashino Public High School, where he meets Nanako Mizuki. His experience taming the rowdy gangs in his assigned class hardens his convictions that teaching is the way to go, and when he learns of Mizuki's problems, he also decides to abstain from sexual experience with schoolgirls, opting to solve their personal issues for them, instead.
Unfortunately, he forgets to take the public teachers' civil service exam; as a result, no public high school will accept him, but he is still eligible for private school teaching. He manages to get a job at the Holy Forest Academy, despite the objections of Vice-Principal Hiroshi Uchiyamada, whom he continues to aggravate well into his tenure. One of the conditions of having the job at Holy Forest is that he must sleep at the school – in the storage room at the top floor, with roof access – and it is here that Onizuka officially starts his career in teaching, when he stops Noboru Yoshikawa from committing suicide.
Onizuka is put in charge of class 3–4, a class so bad it has driven past teachers insane and one to death. Not only does he survive their brutal, bullying tactics, but he also befriends his students, and the backbone to the story of GTO consists of his unique experiences in turning his students around and learning lessons of his own.
Onizuka is capable of great feats of strength, such as arm-wrestling over 100 men of exponential strength, (sometimes 3 at once) in a row and winning. He is also an experienced martial artist, as Onizuka is capable of fending off multiple opponents, even if they are well-armed. However, it was revealed around chapter 190 that because of all the physical damage he sustained since he started teaching, it resulted in a clotted blood vessel in his brain, and that a jolt to his head could either turn him into a vegetable, paralyze him, or kill him.