All those who have come back from the dead are supernatural monsters, but they are not the whole story. There are other kinds of supernaturally or metaphysically empowered beings that have not died, like demons that possess the innocent or werewolves that answer to the moon. The laws of nature include that what lives must die and that while an organism may grow and mature, it may not change species—for example, from a human into a wolf. Supernatural beings defy these laws and others. Their very existence renders the world an unsettling, unsettled and otherworldly place: the principal difference between supernatural films and films with natural-world monsters that take place in a knowable world. To believe in a supernatural figure is superstitious, but it can also be religious, like a belief in Satan. The supernatural entity, good or evil, is an unknown about which we make conjectures. In his book on supernatural horror, Lovecraft called the fear of the unknown the oldest of human emotions.

We may fear the supernatural in general, particularly because we do not understand it. More specifically we may fear supernatural beings, such as demons; supernaturally animated or reanimated people, such as ghosts and zombies; supernatural curses, such as those that afflict werewolves; mortals who are said to have supernatural powers, such as witches, and more. The supernatural itself can be unnerving because it presents us with a metaphysical realm in which knowns are replaced with unknowns, and because it can open the way for mysterious, powerful forces and beings to get at us.