Supernatural things don't frighten me at all, because I can't quite suspend my disbelief long enough to get frightened. When I read a "thriller" book it needs to be very rooted in reality, in the real world - in this world. Unless the events in the book "could happen to me", it isn't frightening to me, you know?
I particularly like books about stalkers, especially when the stalker is smart enough to skirt the law so the victim gets more and more desperate, because there is (seemingly) nothing they can do. I must sound like such a ghoul right now!!! But I'm having trouble finding books that have stalkers but don't have, say, vampires/werewolves, or similar. I also don't like books that are written from the point of view of the police brought in to solve the case - unless they go on to be stalked themselves, I suppose. I'd rather it be told from the POV of the victim.
Does anyone know anything like that? Favorite themes are "if I can't have you no one can" (left the husband, taken the kids and he isn't happy about it and has the resources and smarts to pursue her) and "I don't even know who you are why are you doing this" (a chance encounter means so much more to the stalker than to the victim and before she can think about stopping the stalker, she has to figure out who he IS).