What do you find scary? It is not always the obvious monster in the dark that is truly scary. Sometimes it is the monster in ourselves, people in power, our loved ones, or even that innocent looking child down the street that is the most frightening. Here are some books that might scare you in unexpected ways, and make for a supernatural read at the same time.
I have been focusing on novels published fairly recently, but if you really want to be scared then I suggest looking into some classics. Stephen King's Misery or The Shining will get to me every time. I cannot even read It because clowns already bother me, if I read the book I would be traumatized at the next child's birthday party sporting a clown. No thank you. Like in the Mercy Holling series, what make these so scary is that the action does not seem too far removed from reality. It feels like it could happen, and the worst things are what you see in your mind rather than what is spelled out for you on the page. I remember reading a couple books by Dean Koontz and Robin Cook in the 1990's that seriously frightened me, and though I can almost picture the covers, I cannot seem to recall the titles.
To continue in the theme of slightly older material than check out the work of Algernon Blackwood. The Wendigo and The Willows give me the shivers just thinking about them. H.P. Lovecraft's works are also guaranteed chill inducers and completely disturbing. I am barely even scratching the surface of paranormal stories that can completely freak me out, there are just too many out there to name, but these are my go to materials for when I want a scare from my reading material.