PICCOLO

From Animepedia

Piccolo is the green Namek in the anime Dragonballz. Piccolo actually wanted to revenge Goku for he always desired to prove himself much more stronger than him but was never able to do so. Piccolo wasn't introduced as a friendly being but as a very arrogant type of a person. He was motived to kill Goku after being seperated from Kami and even to rule the world but unfortunately due to Goku's powerful attempts he couldn't do so.Piccolo made friends with Goku after doin' that with his beloved son Gohan when he trained him and even helped to enhance his abilities and to use his potentials . Gohan is the only one in entire universe who can really understand him and Piccolo himself is fond of the young boy.