Now, I for one don't believe the Slenderman exists. But, if he did, then his existence would be quite scientifically impossible. Now, what follows is just my theory, so if you don't like it, then please, hate on me in a logical manner.
So, here's my theory. There are many reports of people seeing the Slenderman all at the same time, in different parts of the world. If we're going by the theory that Slenderman exists, but not SlenderMEN, then we would have a problem here. But actually, we don't. See, people have reported Der Ritter here with a black tie, red tie, dimples for facial features, no facial features whatsoever, ghostly appearance, solid appearance, etc. But if there is just one Slenderman, how can this be? Well, it's because Slenderman's appearance depends on how scared of him his victims are, the version of him they're most familiar with, etc. And, you ask again, how can this be? Well, we've all established that Slenderman can teleport anywhere, at anytime. All he needs to do is see his victim, and plant a growing thought of himself into their brains. They start of curious, and think they see him, then have a hobby of researching on him, and then they know they see then an obssession, where they constantly see him, like once an hour, and, finally, he takes over their brains and shuts them down, giving them the thought that he impales them, rips their heart out, etc.
So, when people say they see him, point to a path by a tree, their friend turns round and sees nothing, it's because Slenderman only appears in the victim's head.
Anyway, do you approve of this theory?
Thanks for reading!