It's funny that when se grow up, the concept of "monster under the bed or in the closet whose creepy appearance we don't know and who eats your feet or hands if they stick out of the bed" becomes a bit ridiculous. So imagine a version that would scare us even as grown ups, with no eyes but smelling fear so sending a gas that makes us picture our biggest fear so it guides it to us and it can kill and eat us. That'd be hella cool for a story.

Boogeyman (fun fact : in French it's "croque-mitaine", literally a "hand-eater/hand-muncher") © Occidental folklore
Drawing, design and theory © me