At first I thought this was the design by Glen O'Neill: http://glenoneill.com/post/5533799495/grimcreeper

But then read in Dave Cheung's comments that an artist "previously commissioned to do it [ran] off and [stole] the idea for his own nefarious ends," so am assuming that would be O'Neill, and if so I am now okay with Dave's design being about 20 times better than the one linked above.