The Slender Man, also written as Slenderman, is an internet meme and urban legend, which branched out across the web as a figure that has established his own mythos. Overall, he is the titular main antagonist of the mythos.
Vote which fictional character would naturally fit in-universe with a big-named franchise! No time-travel, no interdimensional crap, no "Pooh's Adventures", they would just exist in-universe.
