Creatures rule the fantasy genre. Some are allies, some are foes. Some are mean, some are not. Some are good, some are evil. These creatures are utilized, just on a general level, to establish a fictional world. But, where do these creatures fall on the menace spectrum? When and how are they used in storytelling? Personally, the concept of demons doesn't settle well with me, and yet there is a method to using them in storytelling. In some instances, there is a real necessity for them. This is not to say that I do like monsters. But I can say that some facet of a monster is badass in some situations. Some may wonder why they’d ever need to write about a demon, especially if they’re not in a spooky cult or writing a horror story.
The majority of human beings follow a code that essentially revolves around right and wrong, whether it’s rooted in religion or otherwise. The Bible, for example, clearly delineates that. The wrong is considered sin, and from sin comes demons. And that’s the core distinction, in my opinion. A demon is an embodiment of wrong, or evil, and involves a deeper level of thought to understand. They attack a person’s moral psyche. But, we absolutely have to write about the minions of evil that oppose our protagonists. In my opinion, they’re more worth writing about than monsters.
Monsters are more superficial. They’re obstacles. And given a certain perspective, monsters may not seem all that bad. The Kraken (the cheesy 1981 original or the short-lived 2010 remake), for example, is a monster. Though terrible and colossal, it was sent to do one thing: destroy. A good example of a demon would be Hades, the bitter god who deployed the Kraken, or Harry Potter’s Lord Voldermort, both of which were enacted by Ralph Fiennes. Disclaimer: Ralph Fiennes is not a demon to my knowledge. The distinction between the two is a more obvious representation. Demonic entities use a higher level of cognition to manipulate or corrupt that aids in an evil plot, whether it’s their own or whoever’s. Monsters, more or less, behave by their instinct—which, given one’s perspective, may seem better. What if you were in control of the Kraken and used it to crush your enemies? The Kraken wouldn’t be all that bad. But you’d be accused of being evil to some.
Both monsters and demons take on a variety of forms in the world of literature. But, while monsters invite an endless amount of imagination to create, demons reflect a more specific quality of the human world. Demons are strictly evil. Your tall, pale, pointy-eared Elven character may be considered a monster to your grandma, but a charming and polite foreign-exchange student to your bestie. A soul-drinking Abyssian, however, will always be an evil demon of anyone’s worst nightmare. You need monsters. And in some cases, you need demon-esque foes, because they fight for what’s wrong. And if ever one must distinguish the two, remember that it requires a certain level of depth to tap into a demon’s level of monstrosity. Not all demons in the realm of Fantasy-fiction are from the biblical Hell, but you get the idea. You want a good example of a demon? Take the Babadook as an example.