Various theories for the Slender Man's origins have been thought up since the tall man's introduction into popular culture. Slender Man sightings have since been traced as far back as ancient Egypt. Many early 1900s photographs featuring the Slender Man and stories of unexplained fires and disappearances were also brought to light, which were set in various places around the world. Der Ritter ("The Knight"), a sixteenth century woodcut attributed to Hans Freckenberg, which featured a knight duelling an armored creature with multiple limbs, was also connected to the Slender Man legend. The Slender Man was later connected with the story of Der Großmann ("The Great Man"), a bogeyman that had supposedly been sighted in Germany's Black Forest as early as the sixteenth century.
Several aspects of these stories became central to later Slender Man legends, including mention of him murdering hikers and hanging garbage bags containing their organs from trees as well as the entity having some sort of relation to Germany. The Slender Man proved highly popular, with various other posters adding their own Slender Man-related images and stories. Victor Surge posted the first images of the Slender Man, describing him as a tall, faceless man that steals away children. The Slender Man was first mentioned in 2009 in the Something Awful forums' Create Paranormal Images thread.