In this article we are going to explore King Piccolos origin as well as his downfall.
Let's start at the beginning:
300 years before the events of Dragonball, a nameless Namekian, who was sent to earth as a child to survive a catastrophic natural disaster on his home planet, attempted to assume the position of "Guardian of Earth". He was denied the position due to the evil residing inside of him. To achieve his goal the nameless Namekian underwent an intense training and finally managed to banish his evil side creating two seperate entities. The good side, a pure being known as Kami and a being of concentrated evil known as King Piccolo. The two entities resembling ying and yang were eternally linked, if one should perish, so would the other.
Sealed in a rice cooker:
Being the incarnation of evil, King Piccolo created several offspring and terrorized the citizens of earth. However, a martial arts specialist, Master Mutaito, and his pupils, including a young Master Roshi, fought back and killed Piccolos sons.
By the time they finally faced King Piccolo himself the majority of earths population had been slaughtered. In martial arts combat Mutaito and his students were no match for the mighty Demon King. In order to defeat him, Master Mutaito used a special technique called "Evil Containment Wave" also known as "Mafuba" to seal King Piccolo in an electric rice cooker. The price for using this technique was his life.
After King Piccolo had been sealed, Roshi sunk the rice cooker in the depth of the ocean so the evil King could never return.
The return of King Piccolo:
A few centuries later Emperor Pilaf finds the rice cooker and releases King Piccolo. The Demon King then decides to have all the current and former finalists of the famous World Martial Arts Tournament "Tenkaichi Budokai" murdered so that there is noone left who is capable of learning the Evil Containment Wave and he cannot be trapped again. To aid him in his evil plan he spits out two eggs containing his sons Piano and Tambourine who among others kill Krillin. A third son called Cymbal is created shortly after with the task of gathering the dragonballs. Cymbal then encounters Son Goku and Yajirobe and attemts to take a dragonball from them by force. In the fight he is killed by Yajirobe and then roasted and eaten.
When Piccolo senses the death of his son he orders Tambourine to go and hunt down the ones reponsible. Enraged because of Krillins death Goku fight and kills Tambourine. Sensing the death of another one of his children King Piccolo confronts Goku and easily defeats him leaving the severely injured Goku to die. However Goku is rescued by Yajirobe after Piccolo leaves. Meanwhile Master Roshi attempts to trap King Piccolo using the Evil Containment Wave, but misses the container and pays with his life for using the technique.
Since there is noone left to contest him, King Piccolo gathers all the dragonballs and is granted eternal youth by Shenron. Having been returned to his physical prime he is stronger than ever before. In order to prevent anyone else from using the dragonballs against him, he kills the dragon before it can disappear.
The rejuvinated Piccolo then proceed to take over the throne of King Furry by force and rules the world using death and destruction as his entertainment.
King Piccolos downfall:
The evil King is then confronted by Tien Shinhan who also learned the Evil Containment Wave but is unable to seal his enemy away. Since Tien is no match for Piccolo himself he creates a fouth son called Drum who defeats him easily. In the last second a now much stronger Goku arrives and kills Drum quickly saving Tien Shinhan.
A fierce battle ensurs with King Piccolo gaining the upper hand by injuring Gokus knee. He then uses the weakened Tien as a human shield demanding Gokus surrender. With the dragonballs and therefore the ability to revive Tien, Goku complies and lets himself get injured further. Just when Piccolo attacks Goku in order to finish him off, Goku fires a Kamehameha with his right hand, propelling himself toward his enemy, punching a hole through Piccolos chest mortally wounding him. Before taking his last breath the evil King Piccolo uses all of his energy to spit out one last egg containing his reincarnation "Piccolo Jr.", therefore sparing Kamis life.