Piccolo is a fictional character from the Dragon Ball series, appearing in Dragon Ball, Dragon Ball Z, Dragon Ball GT television series and the Dragon Ball Z movies and video games. He is one of the last of the Namekian people, the alien race that created the dragon balls. http://www.dragonballz.com.au/dragonballz/piccolo/ His alien heritage grants him unusual fighting abilities, such as splitting into as many as four clones of himself, and the instantaneous regeneration of limbs. http://www.funimation.com/dragonballz/index.cfm?page=characters&type=&id=46
He is the inventor of the "Special Beam Cannon" technique, a powerful energy attack he used to kill Goku and Raditz in a single shot. http://www.dragonballz.com.au/dragonballz/saiyan-saga/ Piccolo is considered the second most powerful being on Earth. http://www.dragonballz.com.au/dragonballz/piccolo/
Background
When Piccolo first appeared he was known as Piccolo Jr., the last of King Piccolo's offspring. http://www.dragonballz.com.au/dragonball/piccolo-jr/ He sought revenge on Goku for the death of his father at the World Fighting Tournament. He was defeated, but returned to fight Goku just as the Saiyan assault on Earth was beginning.
Realizing neither of them stood a chance against the Saiyans alone they formed an alliance.http://www.dragonballz.com/index.cfm?page=episodes&id=306 Goku sacrificed himself to stop Raditz, holding him still while Piccolo used the Special Beam Cannon to destroy them both. Goku would be stuck in the afterlife for one year, so Piccolo took it upon himself to train Goku's son, Gohan. Eventually Piccolo would become like a surrogate father to the boy, even giving his own life protecting him from the Saiyan invader Nappa.
Quotes
"Even with the energy you took from me, my power is still far greater than your own. " - Piccolo http://www.imdb.com/title/tt0214341/quotes
"Fool! Never believe anything the enemy tells you!" - Piccolo http://www.imdb.com/title/tt0214341/quotes
"My ears do more than just frame my face." - Piccolo http://www.imdb.com/title/tt0214341/quotes
Scene from Dragon Ball Z featuring Piccolo
In this scene from the Saiyan Saga of Dragon Ball Z, Piccolo charges his finishing move, the Special Beam Cannon. Since it takes time to execute, Goku must hold Raditz in place, even though he knows the blast will kill him as well. Raditz sees the rising power level in his scouter and panics. Piccolo unleashes the attack and destroys them both.