Son Goku is the main character in the Dragon Ball story. When Dragon Ball started, the plot evolved around the adventures of Chibi (little) Goku. He was a very powerful boy that carried around an exspanding staff (the nyoi bo) which was given to him by his grandfather, Son Gohan. After returning to the turtle named Tortoise to the sea, he met Kame-sennin who gave him Kintoun (a cloud that he flies on also called nimbus) as a reward. When the story became more action based, the series changed to Dragonball Z. During Dragonball Z, we found out the reason that Goku was so much stronger was because he was a alien from Planet Vejita Known at the saiyaa-jin. This information was given to us by Goku's brother Radditz. goku was originally sent to earth to destroy the planet, but fell off a ravine and hit his head, thus losing his memory. Sometime during Dragonball, Goku married Chi Chi and had two kids, Gohan (who he named after his dead grandfather) and Goten. His father was Bardock who made his apperance in one of Freeza's Flashbacks and in the Dragonball Z series. Once killed by Piccolo's Makkankousappou and the other by second stage cell, when he blew himself up. He was trained by a viriety of people. The one's that I know of are Son Gohan (his dead grandfather), Kame-sennin, Kami-sama, and Kaio-sama. I believe that he trained a little with karin-sama, but I'm not too sure. when Goku was fighting with Freeza on planet Namek, he turned Super Saiya-jin for the first time,and over the course of DBZ Goku was able to reach SSJ3.. Their isn't really much difference between ssj1 and 2 except the hair gets spikier and there is a whole lot of electricity around their aura. In Dragonball GT he went SSJ4. When SSJ4, he gets a new outfit, there is red hair convering his chest, and his hair isblack and just as long as when he is SSJ#. There also is some red outline around his eyes.