Namekian - Extraterrestrial
Piccolo is actually Piccolo Jr., the reincarnation of the original Piccolo who was once joined with Kami as a single, powerful entity. When the entity split, Piccolo set out to rule the Earth but was soon captured and sealed inside a rice cooker.
When he was revived, he was immediately killed by Goku. Before he died, he reincarnated himself in an egg which later hatched and became "Piccolo, Jr.". Hoping to avenge his death, he entered the Tenkaichi Budokai but was defeated by Goku in the final round.
Special Talents and Abilities:
Piccolo has a few notable talents worth mentioning. The first is that he can regenerate any limb on his body with the exception of his head. His signature moves are the Destructive Wave and Special Beam Cannon. Piccolo can also manifest inanimate objects.
While Piccolo is one of the strongest Namekians, he is unable to defeat some of the more notable DBZ villians such as Freiza and Cell, even after fusing with Nail and then again with Kami. His most notable weakness however, is his affection for Gohan - he even sacrifices himself to save Gohan.
Piccolo started out as a really, really bad guy - the evil "half" of a single entity (Kami was the "good half").
It wasn't until after he began training Gohan that he discovered his good side and became a favorite Z-fighter. He fused with Nail to fight Frieza and then with Kami (back to the single entity) to fight the Androids but is almost killed by Cell.
Did You Know?:
Piccolo originally joined forces with Goku to defeat Raditz and then sneak in an attack on Goku as well to avenge his father's death. He then took Gohan under his wing because he sensed that Gohan's power would be useful in defeating other saiyans that would arrive later. What Piccolo didn't count on was liking Gohan and eventually, he became Gohan's biggest fan and even became friends with Goku.