Goku's onetime arch enemy, Piccolo is the second strongest being on Earth. He wears an extremely heavy cape as constant training for his muscles. He is renowned for his powerful energy blasts as well as his ability to split into two or four seperate entities. Green like a lizard, Piccolo has the ability to regenerate any limbs that he may lose in battle. This comes in handy more than once.
Piccolo is a native of the planet Namek. He was reborn from an older, evil Piccolo, who in his last moments of life spat out an egg, which then hatched into this "new" Piccolo. He starts out fighting against Goku to rule the world, but when the Saiyans arrive Piccolo is forced to join forces with Goku and the others to defeat a greater more powerful evil.
At first the alliance with Goku is uneasy, but as the story unfolds, their bond becomes stronger. Piccolo even steps in to train Goku's son Gohan for the upcoming battle against the Saiyans. Piccolo is confused by the bond he sees with Gohan and by his own actions. Is he training an opponent who is stronger than him, and why does he risk his life to save Gohan's? Gohan sees the good within Piccolo and their relationship brings this good out of Piccolo. In the showdown with Vegeta and Nappa, Piccolo saves Gohan's life by jumping in front of an energy blast targeted at Gohan.