A Modern Spirit from the Modern World.
That is all we can tell you at the moment, as Slender-man has not yet been officially added to our Holy Database. We apologize for this terrible omission. There are many Gods in the Universe and only a limited number of Godcheckers checking them.
Please be assured that our team of Data Dwarves have been sent off to find more nuggets of information. Slender-man will be updated soon.