Dragon Ball Z continues the story with Goku as a young adult and father to his son Gohan. Raditz arrives on Earth in a spacecraft, finds his younger brother Goku and reveals to him that they are members of a nearly extinct extraterrestrial race called the Saiyans (???? Saiya-jin). The Saiyans had sent Goku to Earth as an infant to conquer the planet for them, but he suffered a severe head injury soon after his arrival and lost all memory of his mission, as well as his blood-thirsty Saiyan nature. Goku refuses to help Raditz continue the mission and decides to team up with Piccolo in order to defeat Raditz, while sacrificing his own life in the process. In the afterlife Goku trains under the North Kaio until he is revived by the Dragon Balls in order to save the Earth from Nappa and the Saiyan prince Vegeta. In the battle Yamcha, Chaozu, Tenshinhan and Piccolo are killed, and the Dragon Balls cease to exist. Kuririn and the galactic tyrant Freeza learn of another set of more powerful Dragon Balls by overhearing Vegeta and Nappa talk about the Dragon Balls on planet Namek (????? Namekku-sei?). Bulma, Gohan, and Kuririn depart for Namek in order to use them to revive their friends. However, Freeza is already there, seeking the dragon balls to ask the dragon for eternal life, which leads to several battles with his henchmen and Vegeta. Realizing he's overpowered, Vegeta teams up with the heroes to fight the Ginyu Force, a team of mercenaries thought to be some of the strongest in the universe. After Goku arrives, the final battle with Freeza himself comes to a close when Goku transforms into a legendary Super Saiyan (????? Supa Saiya-jin?) and defeats him.
A group of Androids (???? Jinzoningen?, "Artificial Humans") created by a member of the former Red Ribbon Army, Doctor Gero, appear three years later, seeking revenge against Goku. These androids were programmed by Doctor Gero to kill Goku. During this time, an evil life form also created by Doctor Gero, called Cell emerges and after absorbing two of the Androids to achieve his "perfect form," holds his own fighting tournament to decide the fate of the Earth. After Goku sacrifices his own life to no avail, Gohan avenges his father by defeating Cell after ascending to the second level of the legendary Super Saiyan. Seven years later Goku, who has been briefly revived for one day, and his allies are drawn into a fight against a magical being named Majin Buu, created by the evil wizard Bibidi and resurrected by his son, called Babidi. After numerous battles resulting in the destruction and recreation of the Earth, Goku destroys Buu with a Genki-Dama attack containing the energy of everyone on Earth. Goku makes a wish for Majin Buu to be reincarnated as a good person and ten years later, at another Tenkaichi Budokai, Goku meets Buu's human reincarnation, Uub. Leaving the match between them unfinished, Goku departs with Oob to train him to become Earth's new guardian.