Boogeymen

Boogie monsters are a types of monster in Monster High. Boogeymen in myth can be very different from each other in appearance depending on the myth. Some myths say their animal like, deformed humans, looking like witches, or some myths interpret them as ghosts. In monster high that's not the case, as in "Haunted" Twyla needed "boogie sand" to become a ghost. There are different types of boogie monsters all over the world like the, "Wewe Gombel', "El Coco", "Babaroga", and the "Tata Duende" for example.

Discription
In monster high there is only one boogie monster that's ever seen being Twyla, so her appearance is a template for boogie monsters. She has light purple-blue skin, with grey hands and feet. The grey pattern on her hands are swirls invoking shadows. Twyla's eyes can also glow in the dark a trait most boogie monsters may have.

Monster High
In monster high there are only two known ones, one being Twyla the other being her father who's never seen. Though Twyla we know boogie monsters eat nightmares. We also see that Twyla can travel though shadows and can see if anyone is a shadow, but it's unknown if all boogie monsters have these abilities. There is something called "boogie sand", it's sand that can turn anyone into some kind of monster, as shown in the movie "Haunted", when it was used to turn Twyla and the other's into ghosts.

Etymology
The Bogeyman (/ˈboʊɡimæn, ˈbʊɡi-/; also spelled boogeyman, bogyman, bogieman, boogie monster or boogie man) is a mythical creature used by adults to frighten children into good behaviour.