Here's Harry, doing what he does best... flying his broom ridiculously high in the air and catching small objects.  I drew this picture as reference for someone who wanted to make a Harry sculpture, but that's still up in the air, so to speak.

Here are a few attempts to make Hermione's design more interesting.  The top one is way too girly.  I like the one on the right the best, probably because she's being herself.

And here is the ever-cranky Mr. Dursley, one of the first HP drawings I ever did.  He looks like he's about to snap... right?  Okay, maybe not.  Mildly peeved, at least.  I haven't drawn him since... he's not the most amusing character and not in any cool scenes.

Here's an attempt that failed terribly to draw Snape without a beard (he looks a little like an evil, beardless Abraham Lincoln)... I've got a better version somewhere but I can't remember where I put it, alas.