Okay, forget all of that voting nonsense that no one really took seriously anyway. I've found who I would pick to fulfill the role as a RL Succubus. Kelly Brook.
Alan Strutt, a fairly famous skins photographer, captured the above image as part of an amazing Kelly Brook spread you can easily find through a Google search. The lighting, the contrast, the darkness... screams Succubus, doesn't it?
I think so.