Son Gohan is a character in Dragonball Z.
He was born to Son Goku and Chi-Chi, and was named after Goku's adoptive grandfather. Gohan lived a peaceful life (without any training, as per Chi-Chi's wishes) until one fine day when Raditz came along. He revealed Goku's heritage and true name, then kidnapped Gohan. Gohan got so scared that his power level skyrocketed. This allowed him to escape and distract Raditz long enough for Goku to trap him in a bear hug-like hold while Piccolo shot a Makankasappo through the brothers' hearts. But right before he dies, Raditz tells them that more of his kind are coming to Earth to cause destruction.
To prepare for the two coming Saiya-jins, Piccolo leaves Gohan out in the wild to defend himself for many months. Though terrified constantly of the dinosaurs at first, he grows calmer and more self-sufficient, and eventually views Piccolo as a father figure. At one point, he looks at the full moon and turns Oozaru, so Piccolo blasts off his tail, which changes him back. When Vegeta and Nappa arrive, Piccolo takes a fatal blast from Nappa, which angers Gohan yet again, making him attack the burly invader. Right in the nick of time, Goku arrives and killshim, but struggles with Vegeta, who goes Oozaru, and Goku is saved only because Yajirobe chops off his tail.
Gohan's next big part is on Namek, where he, Bulma and Krillen get the Dragonballs and wish for Piccolo to return to life and come to Namek. After Freeza stabs Krillen, Gohan gets mad and beats him up, but then gets beat up himself, and is saved by Dende, a young Nameksei-jin and future Kami-Sama. After Goku goes Super Saiya-jin, he takes Bulma and Krillen back home.
In the Cell Saga, Gohan trains with his father in the Room of Spirit and Time, and ends up being the star of the show for a while. After Cell hurt nearly everyone he loved, he killed Android 16, sending Gohan spiraling with anger to Super Saiya-jin 2, which made him equal parts powerful and sadistic. After taunting him verbally and physically, he became an Ultra Super Saiya-jin, which made him slower because of the bulky muscle he accumulated. Cell kills Goku and Trunks, which made Vegeta go ballistic. Cell shoots a blast to kill Vegeta, but Gohan takes it for him, which cripples his arm. In the end, Gohan finishes Cell off with a Kamehameha powered by him and Goku.
As a teenager, he returns to his studies again at Chi-Chi's forcing, though he becomes The Great Saiyaman in his spare time, posing more than fighting a la The Ginyu Force. He gains a girlfriend, daughter of the "World's Strongest Fighter" and teaches her to fly. He gets his hidden power awakened by the Elder Kai and fights Majin Buu for a bit, but then he gets absorbed like everyone else who fought the pink demon. Gohan is brought back to life by the Dragonballs and donates power to the Genki Dama made by Goku that destroys Buu.
In the end of DBZ, we found that Chi-Chi's conditioning was a success. Gohan married Videl, had a daughter named Pan, and became a scholar.