Goku is the hero of Dragon Ball Z, the most powerful warrior on Earth. When the Saiyans arrive, Goku learns the mysterious secret of his own past: he is a Saiyan formerly named Kakarot. Goku was sent to Earth as a baby to destroy the planet, but a head injury as a child scrambled Goku's programming. Instead of growing up to become a destructive super-warrior, he became innocent and pure of heart, fighting for good.

Goku is peaceful, good natured, honest, loving to his family and friends, loyal, trustworthy, and brave. If he has a weakness, it is his trusting nature. He always finds the good in people when others don't see it, though Goku's enemies sometimes take advantage of his naive trust.