The Boogeyman is the main antagonist of the game of the same name. Each night, it climbs into the player's room with the express purpose of killing them. The only way to drive the beast back is with the player's flashlight, as it has a natural aversion to light (natural or artificial). It is technically possible to see two boogeymen as once, but this only occurs on the hardest level (Halloween nightmare on hard)
The Boogeyman (when viewed from up close) takes the form of a mostly spindly, bald-headed and uncloth humanoid figure.
Its skin is a dark maroon in color, though parts of it are known to glisten when viewed by the light. Its eyes are an unnatural shade of white, with no visible irises to speak of. Its fingers end in long, sharp claws, which are used to great (and always painful) effect on its victims. Similarly, the creature is possessed of a maw full of long, dagger-like teeth, which glimmer in the light.
The only part of it that seems even remotely human is its legs, which have no apparent differences from the normal human being.
This information is found in the Living Room, it is within an open book:
The Boogeyman is said to be a spawn of a witch, who was being hunted after kidnapping a lot of children for no reason. The witch was pregnant with a baby whilst escaping the hunters. Knowing that her child will be caught with her, she casts a spell using a small amount of blood from the kidnappees to protect her child and also gives him some supernatural powers of strength, the ability to see in the dark, climb unhindered, and hide in the shadows unseen.