How can I deal with someone I know is bullying other people?

[Sypheren]

A kid in my school has been bullying other kids for a while, as long as he's lived- I think. Were currently freshmen. He's done, and gotten away with things varying from getting a group of people to exclude another kid, to grabbing someone and punching them in the temple after seeing the end of a fight that he wasnt involve in, and to make things worse, he hit the kid that was attacked and had defended himself. Personally, I've only had one encounter with him in football, where he grabbed my helmet by the face guard and tried to bring me to the ground. I grabbed his hand (keeping it locked on my mask) and jerked sideways, he left me alone after that.

I really don't like watching him bully other kids, any ideas on what I can do to stop him or get him caught (he's evaded all of my previous attempts because his father always gets him out of it). Any help is appreciated!