Piccolo

Piccolo is the reborn Devil himself. Many years ago, A Namekian was sent to earth in fear that a comet would soon hit the planet Namek. The man we know as Kami-sama (which translates into god or the god of earth) wanted to take the place of the watcher of earth. But in order for him to do that he had to purge the small amount of evil that was within him. When Kami-sama did this his spirit split into two. Thus, from the expulsion of Kami's evil side, was the birth of an evil entity called Piccolo-Diamao (Piccolo the demon). Piccolo-Diamao was evil and destructive causing cities to disappear. Eventually this evil being came across Goku (when he was young). They fought an epic battle, with Goku killing Piccolo-Diamao. On his dying breath he spat out an egg which hatch into the Piccolo in the Z team.

Young Piccolo was evil like his father. A native of the planet Namek, he has the ability to regrow parts of his body that he lost. He and Goku were enemies as teenagers and fought many times. However when he was forced to train Goku's son Gohan before Vegita and Nappa were to come to earth, a different side of Piccolo is revealed and we see that he is not entirely evil after all. Gohan's innocence and friendliness help Piccolo become a different person changing him to be on the side of good instead of evil. Further in the story Piccolo develops a paternal affection for Gohan, protecting him. During the Android saga, Kami-sama nulls on the decision to remerge with his "evil" counter part noting that Piccolo has good in his heart. Kami eventually decides to do so forever putting him on the side of good and fighting with the Z team.