The sensible answer would be to tell the head teacher, or get your parents to talk to him/her or the school board, if that fails then..

Well, to be completely honest, the only real way to get him off your back, if to beat him senseless, preferably infront a crowd. It's risky, but if done correctly, makes you feel the king of the universe.

I'd give tips on how to beat said bully senseless, but I don't think it would be approved on here