I've been sitting here trying to remember the name of some I'd read not so long ago, even browsed through my books on Goodreads... then after about 15 minutes of puzzling over it I realized that they weren't books, they were stories on the
NoSleep subreddit.
A direct link sorted by highest rated posts of all time.
They also do
ebooks.
For those who aren't familiar, people post their original stories, and the rule is that commenters must respond as though the stories are true. That leads to some very interesting discussions. But one doesn't need to read comments to enjoy the stories there.
I'm a long-time horror fan, and some of the scariest, creepiest stuff I've read is on there.