Goku also known as kakarot  is a Saiyan raised on Earth Kakarot originally was sent to destroy Earth as an infant, there he would be adopted by Grandpa Gohan who named him Son Goku. A head injury at an early age alters Goku's memory, ridding him of his initial destructive nature and allowing him to grow up to become one of Earth's greatest defenders. He constantly strives and trains to be the greatest warrior possible, which has kept the Earth and the universe safe from destruction many times