I tend to go for cult movie characters every year, usually ones who smoke as much as I do (that way my ever-present cigarette could be somewhat considered a prop).
Last year I was Mia Wallace from Pulp Fiction, post-overdose obviously. Just bought a cheap white button down, a fake syringe, and a ton of fake blood. So chic.
This year I'm trimming my bangs, donning a choker and going as Mathilda from Leon: The Professional. Stuffed bunny included.