Most upvoted comment
What’s the scariest story you’ve ever heard? Real or fake. Internet or not.(r/AskReddit)
Penpal. Originally published on /r/nosleep by /u/1000vultures. Absolutely terrifying.
*Edit: Holy cow this is easily my most upvoted comment ever. Glad you guys are enjoying the creepiness. As several other people have pointed out, /u/1000vultures has actually published this as a full-length book, with some new stuff added in and edits as well to make it all flow better. If you enjoyed his stories for free, please consider buying them!