How do you make someone Happy again?

I have a friend and, even though he hides it well in public, I can tell he's depressed and often bullied. He's really funny, and makes me laugh a lot, but everyone else views him as "that one annoying kid" which really angers me cause he's really nice if you bother to get to know him. Like I said, he makes me laugh a lot and smile, and I wish I could do the same for him because I worry. Any suggestions?