Without going into specifics so the creature/entity/plot is given, I'm looking for horror that is keep-you-up-at-night level. A good wendigo or poltergeist or even disease epidemic book would be greatly appreciated.

I loved books like Pet Sematary, the Troop, The Quiet Boy (short story), Contagion. I try to go into horror blind so I am fully unaware of what to expect, so I've read a lot of duds lately. Psychological horror is ok, if it's unpredictable/not just "normal person gaslit into thinking they're crazy" type trope.

The only horror I was unable to finish was Tender is the Flesh. My kudos to you if you got through that one.

Thank you all for your advice