What to wear to the Harry Potter midnight premiere?

I'm so freakin' excited I actually got tickets! :D:D:D

I'm going with a big group and we're all dressing up. I have oversized
dark coats that kind of look like deatheater robes, I have big glasses
that are very Harry Potterish, and I a lovely wand made out of paper.
:P

I wanted to do something kind of creative though. I have short, pixie
styled hair so I'm considering mimicking Tonks. Any other suggestions?