Goku was born to a bounty-hunter saiyan, Bardock, who happened to be the first Saiyan to reach Super Saiyan 3. He crashed landed on Earth before the Nameks destroyed the planet of Saiyans. He was found by a man named Gohan, who always wanted children. He made Goku his "grandson" and trained him to be a warrior. Gohan died mysteriously and sent Goku on a quest to find Gohan's teacher, Master Roshi. When Master Roshi was finally found Goku started training with him. Soon after, a boy named Krillin washed up on Master Roshi's shore, he had lost his memory and all he could remember was his name was Krillin and he liked turtles. Goku and Krillin trained with Roshi until Roshi gave him a four-Star dragonball, thus starting the series, Dragonball.
DragonballGoku along with his freind Krillin went after the dragonballs. Soon a girl named Bulma joined them. Later, a girl named Chi-Chi also aided them. An evil force named Piccolo arised, Goku had to stop him. Piccolo killed Master Roshi, sending Goku on a rampage as an oversized ape. Later Piccolo was stoped and Master Roshi was revived by the Dragonballs.
Not long after that, Piccolo had divided him self into four individuals, Piccolo Jr. (the Power), Drum (The Anger), Flute (the Pain) and Kami (the Wisdom). Goku and his friends were able to stop Flute and Drum, but Kami and Piccolo Jr. formed a new good Piccolo who would join them on their quest.
Goku learns that he has a brother named Vegeta, who comes down, and discovers he is a Saiyan. During the battle, Goku ascends to Super Saiyan and ultimately defeats Vegeta.