Well, I don't know about horror movie monsters, but I once dated this guy who was so creepy that he was almost perfect for me. He was intelligent, artistic, attractive... though it was difficult to keep a relationship between a pane of glass, and we had to go our seperate ways. Besides, towards the end we'd just be having a conversation about something like serial killers or lambs and he'd randomly make a comment about eating my flesh. Not in the good way, either.
It's surprisingly easy to agree on a place to eat when you're dating a cannibal.