The Slender man is a mythical being with the ability to stretch his arms and torso to inhuman lengths in order to induce fear and ensnare his prey.
Not much is known, as no specific information has been found about his origins, but his objective and habitat are made very clear. He has the need to kidnap children, and is seen right before the disappearance of a child or multiple children. He seems to prefer fog enshrouded streets and wooded areas as a way to conceal himself from being noticed. It should also be noted that children have been able to see him when no other adults in the vicinity could. Children also have dreams or nightmares concerning The Slender Man before their disappearance.