If you have been known that The slenderman legend comes from Germany, it'll probably not be the truth.

And I think many people in here misunderstand it. So I brought good info

According to this site:

https://www.geister-und-legenden.de/der-grossmann

It's basically german blogger site and the title says:

I'll just show you the last paragraph. This blog is pretty long.

The last paragraph of this blog says..

"Was haltet ihr von der Legende des Großmanns? Findet ihr es in Ordnung, solche falschen Legenden zu erschaffen, um eine andere Legende glaubwürdiger erscheinen zu lassen? "

Roughly means

"What do you think of the legend of the great man(The slenderman)?

Do you think that it's okay to create fake legends like this to make another legend appear more believable?"

(Hoax)

If you want to know more about this then enter the site above.