Piccolo

The demon lord Piccolo split from Kami when Kami tryed to become the keeper of the earth.  When Goku was little (in Dragonball not dbz or gt) he killed the evil Piccolo by flying at him and going right through his chest.  Before he died he spit an egg out of him mouth which hached into the Piccolo we all know and love...
He grew up hating Goku for what he did and swore he would kill him until he had to fight along side him against Radditz.
after that they never fought again.

Piccolo has a very close relation ship with Gohan since he trained him when Goku died.  He even died for Gohan when Nappa trys to kill him.

His best attacks..
(I hope I spell it right)
Masanka
Makankosappo (in th English vertion its beam something fire very stupid)