* The Conqueror Worm is a gigantic caterpillar-like EldritchAbomination that does nothing except eat, and grow, and eat, and grow some more. If Hellboy and Roger hadn't stopped it, it would have continued doing this until [[ApocalypseHow it has eaten everything on the planet]].
* The Crooked Man's face is extremely [[http://4.bp.blogspot.com/_edfdVc9_vCE/S1R3Eh7Dg8I/AAAAAAAAAog/Ps_JYdvCil8/s400/Hellboy-The+Crooked+Man2.jpg unsettling]].
** From the same story, we get a witch that can take off her skin and turn into a raccoon, the deformed descendants of the colonists who disappeared from Roanoke and the general creepiness of the setting in the Appalachian Mountains.

* The Tooth Fairies. They sound cute, until you consider the fact that getting caught in a swarm of them means that you are EatenAlive.