This MOD added the well -known Slender Man into Minecraft.

The author also recommends that you try the Slender -Reimagined of iChun's production.

This module Minecraft Forum's original post and the download address provided by provided are all invalid.

But there is an unofficial Project on CurseForge uploading the original 1.6.2-1.7.10 Forge version: SlendersStalgia (The Slenderman by Colossali).