Slenderman

Slenderman or Slender Man or Slender is a villain from "Creepypasta" stories and even has his own horror game named after him (some say he might be real and barely seen like Bigfoot, The Loch Ness Monster, Mothman, or The Abominable Snowman). He is part of a gang that Herobrine has and is also one of his friends, other members of Herobrine's gang include Zalgo, SCP-173, and Happy Appy.