So many monsters, so little time

I have been reading (well, skimming) a lot of D&D monster books over the last few months. Like, a lot. 

As a result, I have now seen what feels like approximately one million extremely minor variations on each of these monsters:

1. A plant which comes to life and beats you to death / strangles you with vines / shoots thorns at you. 
2. A statue which comes to life and beats you to death.
3. A skeleton, ghost, or zombie with a stupid gimmick and far too many hit dice. 
4. A mashup of two or more real-world predators.
5. A race of big dumb humanoid brutes who love violence.
6. A race of giant, hungry, alpha-predator monsters who love eating people.
7. Innumerable pointless giant, golem, and dragon subraces. ('Marsh giants and bone golems are completely different from bog giants and skull golems!')
8. Some random creature with snake parts, spider parts, and/or tentacles glued onto it for no fucking reason.
9. A zillion different demon types which all boil down to 'it looks ugly and it wants to hurt you'.
10. A variant on a classic monster but BIGGER and with MORE SPIKES.
11. A variant on a classic monster but made of fire / ice / poison gas / thorns / knives / whatever.
12. A mindless blob monster that dissolves people with acid.
13. A giant heap of animated corpses all stuck together. 
14. A sneaky thing that jumps out of a shadow and stabs you to death.
15. A robot with a sword.

It brings home to me just how much of the conceptual territory for D&D monsters was soaked up by the original Monster Manual (and, to a lesser extent, the Fiend Folio and Monster Manual II): people setting out to write new monsters now are like settlers looking for new homes in territory where all the best land was taken forty years ago. The original Monster Manual was able to take every concept and present it in its purest form: footsoldiers of evil? Orcs. Big dumb thugs? Ogres. Terrifying boss monsters? Dragons. Everyone since has had to find narrower and narrower niches between the spaces which have already been taken. 'It's like a minotaur, but with six arms! It's like an ogre, but made of poisonous metal! It's like a troll, but with the head of a wolf!'

At the heart of this problem (like most others) is a basic tension between supply and demand. There's no limit to the number of monsters the game-as-written can contain: you can fill your shelves (or, more likely, your computer) with as many monster-books as you can be bothered to read. There is, however, a pretty sharp limit on the number of monsters the game-as-played can contain: regardless of how many monster ideas you have, you only need one session's worth of monsters per session. If every monster was equally useful, you'd expect the result to be increased variety; if the GM has a thousand monsters in his books, and only needs, say, five per session, then you could play weekly for almost four years without ever meeting the same monster twice. In practise, though, a glance at published modules, actual play reports, and everyone's real-life gaming experience confirms that this isn't what happens.

A handful of highly-popular monsters, almost all of them from the original Monster Manual or Fiend Folio, get used endlessly: goblins, orcs, ogres, skeletons, zombies, ghouls, elementals, lizard men, and so on. A second group of monsters, mostly just as old or very slightly newer, get used when GMs want something a bit more colourful: Githyanki, mind flayers, beholders, modrons, etc. And then all the rest - which, at this point, means something like 95% of all the monsters which have ever been published for D&D and its derivatives - is left fighting over the tiny 'novelty monster' slot that remains. Goblins and zombies have probably been used by every person who's ever run D&D for more than a few sessions. How many have ever used, say, the Bearhound? (It's an intelligent talking 10 HD bear with the teeth and tail of a wolf, which has the magical ability to make friends with other animals.) Two? Three? It's not even that bad a monster, as these things go; I can see one fitting very easily into a fae-themed adventure. It's just not good enough for most people to have any reason to use it instead of a dozen other things in actual play.

By the time they got to Monster Manual Five, they were really scraping the barrel.

On reflection, I think that modern monsters are most likely to be useful (and to be used) if they bring a whole scene or scenario with them, rather than being modular plug-ins that can be slotted into almost any game with a minimum of fuss. This may seem counter-intuitive, but let me explain with an example: in the course of my monster-manual-reading binge, one line I got absolutely sick of reading in monster descriptions was 'these undead creatures are often found guarding ancient tombs'. In theory, this means the monsters are easy to use: just drop them in as a guardian of whatever graves, mausoleums, sarcophagi, or whatever you have lying around your dungeon. In practise, though, it virtually guarantees that they never will be used, because there are already several hundred undead monsters which could do the same job, and honestly 90% of the time people will just use a wight or a wraith or a mummy instead. Whereas a monster which carries something more specific with it - a scene, a story, a cultural context, a narrative or an environment or an adventure which its existence generates or implies or requires - can be used as a kind of mini-module, something that someone might read and think: 'huh, I'd like to run that at some point', and which thus has a much greater chance of it making its way into actual play than it would if it was just Minor Lizard-Man Variant #432.

Take, say, the Moon Apes from Fire on the Velvet Horizon. They're cool and weird-looking - big red-black frog-ape-monsters with vertical mouths whose bite induces confusion and forgetfulness, making people deny the very wounds that they have just sustained - but if that's all they were, they probably wouldn't see play, because D&D has about a thousand weird-looking ape-monsters with special attacks in it already. But there's more to them than that: they're parasites who live in the bodies of dead cloud-titans, who swing down to the surface on loops of cloud to bite people and steal valuables and children, and then vanish back up to their lairs with their loot, leaving their victims so befuddled from the effects of their bites that they have no idea what's just happened to them. There's a whole implied adventure, here. Scene one, PCs come across a devastated and looted community full of people with weird bite wounds, none of whom is able to give a coherent account of what has attacked them. Scene two, PCs try to work out what the hell is going on. Scene three, PCs find a way up to the cloud-lair of the moon-apes to kill them and take back what they've stolen. Now, maybe you don't like the sound of that adventure, and that's fine; but if you do like it, and if you want to run it, then the moon apes will be an essential part of it, and as a result there is a decent chance that they will get used. Whereas without that context they'd just have been one more entry on a long, long, long list of monsters that might leap out from behind the next bush and try to kill your PCs, with no more chance of actually making it into play than any other. 

In nature, every organism is engaged in a Darwinian struggle for survival. The same is true of D&D monsters, except that what they're competing for isn't food and territory, it's use in actual play. A monster which brings something to the game, whether in the form of a vivid scene or an interesting tactical challenge, will get used more than one that doesn't; being used will grant it more exposure, which will lead to it being used by other people, and so on. The main ecological spaces are already taken: nothing is going to replace the goblin or the zombie any time soon, and just writing yet another 'big thug monster' and expecting people to start using them instead of trolls and ogres is usually going to be something of an exercise in futility. But there's no reason that new monsters shouldn't thrive within their own niche ecosystems if they're given the chance!