Created by series creator Akira Toriyama, King Piccolo came out as one of the first pure evil character. Previously all the antagonist were somewhat gullible, such as Pilaf of some of generals in Red Ribbon Army. Just to demonstrate how evil he was, King Piccolo's story arc was started by murdering Krillin and stealing a Dragon ball.
When he made his appearance for the first time, he had appearance of being senile, but he was still strong enough to defeat Goku and his allies including master Roshi. Later by using the power of Eternal Dragon, he was able to regain his youth.
Major Story Arc
Many years ago King Piccolo was seal by Roshi's master Mutaito. However King Piccolo was again released by Pilaf
and instantly returns to his diabolical ways of murder, genocide, and greed, attaining the Dragonballs
to restore his youth and even going so far as to destroy the Eternal Dragon
so that he cannot be stopped by a wish. Piccolo declares himself Demon King for the second time and conquers the globe, letting crime run rampant. He was again stopped, but this time permanently (or so it seemed) by Goku
after a long and gruelling battle. Piccolo, however, vomited his offspring into the distance and exploded shortly afterwards. The egg Piccolo Daimao had sent away contained his reincarnation, Piccolo Jr
., or Ma-junior, who would eventually leave his evil ways and become a champion of Earth.
King Piccolo since has made many appearance in Dragon Ball game.