Goku
Goku is the hero of Dragonball Z. He is a peaceful, good-natured, honest, trusting, and protective soul. He is also the most powerful warrior on Earth and the first to become a Super Saiyan in over 1000 years. Having honed his skills and strengthened his spirit to a level never achieved by any being on Earth, Goku is able to fly, shoot energy beams from his hands, move at incredible speeds and, when in a pinch, power-up to a fighting level so high it creates an energy aura around his body and makes him turn blond with green eyes... becoming in effect a walking nuclear war. Goku hasn't learned these skills just for fun, his life is forced down this path as he battles the evil Saiyans in the final battle to save the Earth.
When the Saiyans arrive on Earth it is a shock in more ways than one. Goku finds out the mysterious secret of his own past: he is Saiyan formerly known as Kakarot who was sent to Earth as a baby with the mission to conquer the planet. Luckily for Earth a near fatal head injury "scrambles" his programming and instead of becoming a destructive super-warrior he becomes an innocent pure-of-heart defender of Earth. Goku was raised by a peaceful, wise old man named Gohan, after whom Goku later names his first son. Goku is always there to help his family and friends and he is very protective of them. If he has a weakness, it is his trusting nature.
Goku has many powerful fighting techniques including the powerful Kamehameha Wave and the Kaio-ken which he learns from King Kai. His last and most powerful weapon is an immensely powerful energy ball which garners energy from all sources on the planet, concentrates it into one sphere, and then releases it in one mighty swoop. This ball can be used only once and must be guided carefully for it can destroy the planet if used inappropriately.