Son Goku (孫 悟空 Son Gokū?, addressed only as Goku in most English adaptations) through constant training, Goku has achieved many abilities; aside from his great strength, he also possesses super speed, reflexes, and the power to fly by using chi (舞空術). Goku's also learned Master Roshi's signature technique Kamehameha (かめはめ波 Turtle Striking Wave?). Another signature technique of his is an attack that multiplies the user's chi for an instant, called the Kaiô-ken (界王拳 World Fist?), taught to him by King Kai. Goku's most powerful attack is the Genki Dama (元気玉 Good Spirit Ball, renamed the Spirit Bomb in the English dub?), a powerful sphere created by gathering chi energy from surrounding life forms, which he also learned from King Kai. Goku also learns a teleportation skill called Shunkan Idô (瞬間移動 Instant Movement, renamed Instant Transmission in the English dub?), which he learned from the inhabitants of a fictional planet called Yardrat.
Goku is also the only Saiyan in the series to achieve all the Saiyan transformations seen in the manga. In Dragon Ball, he is able to transform into a gigantic ape called an Oozaru, albeit after his Saiyan tail is removed by Kami, he loses the capacity to achieve this form. However, in Dragon Ball GT, Goku is able to use this transformation again after regrowing his tail using the Elder Kai's help.
During the events of Dragon Ball Z, Goku becomes the first Saiyan in a millenium to transform into a Super Saiyan after being overcome with rage by the murder of Krillin by the hand of Frieza and as the series progresses he achieves every single advanced level of Super Saiyan. Each transformation changes Goku's appearance and enhances his abilities. Goku can also fuse with Vegeta and create a warrior who has the combined power and skills of both. One method is by using the Potara Earrings presented to Goku by the Elder Kai, which results in a 'perfect fusion' creating Vegetto. The other method is by performing the Metamorese Fusion Dance, which creates Gogeta.