In European myth and folklore, monsters serve a very important function. They are a warning. The etymological root of the word is the latin monstrum. Monstrum was a sign or portent which disrupts the natural order due to divine displeasure. This is seen throughout myth and folklore.
Do bad things and the Krampus will come and beat you with a switch. If you venture into wild places, be cautious, for Long Lamkin lingers in the moss and he will do mischief against you. Work hard and spin your flax or Mother Perchta will slit open your stomach, pull out your guts and stuff you full of straw and rocks. Monsters behave in ways that are transgressive. They threaten the moral and social structure of society and humans can invite them in by their own transgressions.
Many of the monsters in D&D are borrowed from myth and folklore. In myth, monsters are enemies of the natural order and civilized society. Allow a monster to live, it will cause destruction. Destruction is its nature. It cannot do otherwise. Monsters cannot be redeemed and must be destroyed to preserve the community, the tribe or civilization. Grendel doesn’t knock politely and ask for hospitality. He storms the hall, dismembers and eats the guests. The cyclops doesn’t invite Odysseus and his crew in, he eats them. Our heros respond in the proper heroic fashion. They kill the monster.
Lots of monsters in D&D were borrowed from sword & sorcery pulps, creature features and fantasy fiction. Some of the most commonly used and iconic D&D monsters come from The Lord of The Rings. I find the way those creatures were used in original D&D as unfortunate because that error has been carried over into the present day. Monsters in D&D seem to me to primarily have the function as foes for PC’s to kill and loot. In myth and folklore, monsters served a much greater function.
Probably the most important fantasy author of the 20th century; JRR Tolkien had a deep understanding of the function of monsters in literature. His work as a medievalist and philologist informed his understanding of monsters. In fact, his essay Beowulf and the Critics transformed the field by recognizing that Grendel, Grendel’s mother and the dragon were not merely entertaining foes for Beowulf to fight but important symbols and central to the themes of the narrative. The primary theme of Beowulf, for Tolkien, was that humans must fight against monstrousness, the afformentioned transgression against the natural order and civil behavior. Thus we see in Tolkien’s creations, the monsters of The Hobbit and The Lord of the Rings are opposed to the free people of Middle Earth, always seeking to destroy. They never create in the positive sense, they only corrupt what is already made or make attempts at creation (in the case of Melkor and Sauron) which are corrupted at their core.
An error that I think Gary and many other game designers have made is to make monsters a sort of natural phenomenon. In Keep On the Borderland the Caves of Chaos have notations in the room keys for so many young and female monsters. The monster manuals also have similar notes. This is a mistake. Monsters are not, cannot be natural. Properly understood, monsters are abominations, creations of the enemies of civilization or enemies of the gods and servants of Chaos. There is only one way to deal with them. Destroy them. By giving them a sort of biological explanation for their origin, Gary made them a natural phenomenon. This leads to the dreaded question, “Is it moral (lawful good) to kill the orc babies?” This has been endlessly argued over and over. It’s a stupid argument and easily avoided.
I have a simple and easy solution. Monsters are abominations or occasionally brute manifestations of natural phenomenon (elementals for example). They should be destroyed for the good of the community. Full stop. They don’t have disgusting little babies or mates.
In my campaign settings monsters are the result of…
- Spontaneously generation/Emergence from the cosmos: Goblins come from collections of excrement and trash. Middens, sewers, cess pools and trash heaps. They are everywhere in a city, particularly in any city where there is an underground sewer. Slums are rife with them. They are as common as rats. Demons emerged from the swirling Chaos of the Void.
- A Wizard/Mad Scientist/Alien Did It: I use Gavin Norman’s brilliant The Complete Vivimancer extensively in my campaign. A lot of monsters were created by crazy ass wizards messing with things they shouldn’t be messing with. Owlbear anyone?
- A Demon/God/Old Ones Did It: Immortals have their own inscrutable purposes why they do anything. Sometimes they are like, “You know, I’d really like to fuck this hot multi tentacled thing with 100 heads.” Other times they need guards, jailors, torturers or servants so they create them.
- Undead: The improperly buried, animated by a necromancer, punishment for being an asshole in life, murdered/violent death and can’t rest etc. Obviously unnatural
Monsters are always bad. Kill them with fire. Except when they are immune then kill them with something else.