Slenderman (or Slender Man) is an elongated or distorted humanoid creature with branching appendages that have been described as arms, branches, or tentacles. It is indistinct or hard to see but appears to be wearing a dark or black suit; no two witnesses have reported the same description for its face, the only exception being its blank white eyes. It reputedly has hypnotic properties or powers, and frequently abducts children. Most victims are never found, but a rare few are discovered, their bodies badly mangled. Reports on this are conflicting and unreliable though, as surviving witnesses are often driven to madness and physical evidence is rare if not nonexistent.

The Slenderman often appears in or near wooded areas or in heavy fog where it is best camouflaged, either by blending in with branches or simply hiding in the fog. Its victims, as stated above, are most often children playing near these wooded areas, who reportedly see the creature in nightmares in the days leading up to their abduction. Most are never found afterwards.