I'd say Stephen King was my biggest influence because I was reading his work when I was ten years old. Anyone who has written a post-apocalyptic novel needs to give a nod to The Stand. I'd call it the gold standard. 

Christopher Moore was a big one, as well. In my eyes he is the godfather of humorous horror. Until I picked up Practical Demonkeeping, I didn't think there would be a market for my style of writing.