This was a true story and it was found in YouTube.

One day a little girl calls the police station this was their conversation.

Girl: Hello?! Police please come me and my brother were followed by a man in a suit.

Police: Stay calm. Where are you?

Girl: In my house. The man is standing by a tree*gasps*

Police: What?! What is it?!

Girl:*sobbing* he has n-no face. Please come faster!!!

*Static*

Creepy Voice: they belong to me

Police: what was that?!

Girl: *Still sobbing* I don't know but please come quick! *gasps* H-he is at my window

Police: Okay calm down bring your brother to a safer room

*girl screams and glass breaks*

Girl:Hello the tall man just wanted to play we are okay now thanks for trying to help.

Police:What is happening?

Creepy Voice: they are no longer here. I shall take the little girl you call Mary Anne.

Police: What the Hell! How do you know my daughter's name?!

*Hangs up*

Police: Hello?! Hello?! Answer me!!!Oh shit I need to go home.

This might be proof for Slenderman. This is a real event and it was also on the news a long time ago. It was recorded and I will try to find the link for this.