This is a character in a comic called Brawn. I met the creator at Comicpalooza a few years back, and after doing an ink commission for him of this fellow that I was deeply unhappy with, I went home and tried again with digital.

The character isn't actually a rabbit. The main character has had his body and mind messed with as part of an experiment, and whenever he encounters the guy in charge, his mind sees a bunny instead. Just, you know, a 6-foot bunny with a suit and fedora. It just screamed for the noir treatment!