My world

The Slender Man is a mythical creature described like a tall, thin figure wearing a black suit and a white face without facial features. He can stretch or shorten his arms, he has tentacles wich come out of his back and he can teleport him self at will.

The Slender Man is commonly said to stalk, abduct, or traumatize people, particularly children. This can cause memory loss, insomnia, paranoia and hotograph/video distortions. 

 On June 10th, Something Awful user Victor Surge posted two black and white photographs of unnamed children with a short description of “Slender Man” as a mysterious creature who stalked children. 
This is one of the description and his photo:

One of two recovered photographs from the Stirling City Library blaze. Notable for being taken the day which fourteen children vanished and for what is referred to as “The Slender Man”. Deformities cited as film defects by officials. Fire at library occurred one week later. Actual photograph confiscated as evidence. – 1986, photographer: Mary Thomas, missing since June 13th, 1986.

There is a game about The Slender Man, if you like it and if you have enought courage, you can try it 

http://slendergame.com/

I don't care if you belive or not, but if you see him personaly, then, your live will be at a nearly end.