Son Goku, born by his Saiyan name Kakarot, is the main protagonist of the anime series Dragon Ball. Along with Vegeta, he is one of the last pure-blooded Saiyans.
Goku was originally sent via capsule to Earth to enslave and conquer the planet. But when he arrived, he sustained a fatal head injury. The people of Earth took Goku and nursed him back to health. As a result of the injury, Goku forgot all about his original mission and his past. And due to their kindness, grew up on Earth as its guardian.
This is the version of Goku from the original Dragon Ball manga, Dragon Ball Kai, and the Dragon Ball Super anime. His counterpart from the Dragon Ball Super manga is here.