In the worlds of D&D, there are countless monsters that terrify the general populace, but only a few truly strike fear into the heart of adventurers. Not because they're so powerful, mind you, but because they're really annoying. Here are a dozen player-tormenting monsters beloved by cruel Dungeons Masters.
Top image by DeviantArtist Dangercook.
1) Rust Monsters
There are a lot of creatures from our Most Memorable D&D Monsters list here; this is not a coincidence. This is because people tend to remember the monsters that completely screwed them over better than monsters that didn't. The most classic obnoxious D&D monster has to be the rust monster, which should be nothing more than a larger-than normal, aggressive prawn-armadillo hybrid, but is in fact completely terrifying because it destroys players' weapons and armour, leaving them defenseless and offenseless -- at which point even a large prawn-armadillo can be a problem. More importantly, the rust monster does not discriminate, and will destroy super-powerful magical weapons and armour just as easily as normal ones, which just terrifies players. I have seen characters that can kill dragons without breaking a sweat run screaming from rust monsters.
Any adventuring party with decent experience and a mage or priest probably won't have too much trouble against a shadow, which is… wait for it… a shadow that can hurt you. But for the low-level party, a shadow can be as deadly as any dragon. The only way shadows can be harmed is with certain magical spells and enchanted weapons, and if you don't have enough of either, all can you do against a shadow is run someplace well lit and hope for the best. Otherwise you're all a bunch of doofuses swinging your swords around wildly while you slowly, but surely, are stabbed to death.
3 and 4) Lurkers and Trappers
When D&D was originally created, monsters were designed almost exclusively to kill adventurers as they explored dungeons, which usually meant the monsters were designed to kill the players with force or with guile. In the latter category, monsters that disguised themselves as ordinary things were popular among DMs and hated among PCs, few moreso than the Lurker and Trapper, who were basically killer ceilings and floors, respectively. The Lurker was a giant manta ray that clung to the ceiling and dropped on adventurers; the Trapper waits until someone walks over it and then wraps up its victims. Just one of these guys and you'd make players stab the floors and ceilings of every room they walk into.
In the same vein, the mimic is creature that can look like pretty much anything stone or wood (like a door), but usually settles as a treasure chest because the humans who enter the dungeons where they live are almost exclusively greedy arseholes. The Mimic's skin is incredibly adhesive, so adventurers who try to open the chest are stuck, and the Mimic sprouts a pseudopod to bludgeon its prey to death (or at least unconsciousness). The best part of a Dungeon Master using a Mimic, much like Lurkers and Trappers, is forcing players to careful poke every other treasure chest they see with a stick for the rest of the adventurer.
6) House Hunters
House hunters are a special breed of mimic that basically disguise themselves as buildings -- young ones are sheds, while ancient ones can look like entire temples or towers. Think having a ceiling-sized manta ray fall on you is annoying? Try having an entire room try to eat you -- and then realising all the rooms around you also want to eat you, too.
7) Gas Spores
Beholders are pretty deadly and terrifying all by themselves, so to add Gas Spores to your adventure is really nothing but a sign that you hate your players. The Gas Spore looks exactly like a Beholder, except when a panicked fighter desperately stabs it, it explodes. Its entire existence is to trick PCs into hitting it and then blowing up, doing an immense amount of damage especially to the poor dope standing next to it. The Gas Spore is pretty clear proof evolution is fake in the realms of Dungeons & Dragons, because they were so clearly designed. Not intelligently designed. Just designed.
Although there is no score in Dungeons & Dragons, there are actually two ways for players to keep score: gold and experience points. We'll get to the latter below, but as for gold, well, half the reason anyone bothers entering a dungeon in the first place is the hope of finding the treasures inside. So the Aurumvorax is a particularly terrifying monster in that it eats that gold the players have so carefully accrued. It looks like an evil, eight-legged badger, but it's also quite an arsehole, and will definitely mess you up if you interrupt it when it's dining on your savings account.
9) Bag of Devouring
Although frequently thought of as a (cursed) magical item, a bag of devouring is in fact a creature, albeit one living in another dimension, whose mouth jus happens to coincide the bag's opening. So not only do players lose what they stick in there -- which can include magical items like potions, magical rings, and most especially sweet, sweet gold pieces -- if they put their hands in there to try and find something, the bag-creature takes that as a sign dinner is served. And it's not like this thing just bites off hands; the bag opens wide and tries to devour the poor bastard whole. If he's successfully eaten, the dude is digested within a single round. So not only does the player lose his character, he has to tell people he fought a purse and lost.
10-12) Wights, Vampires and Succubi
You may have noticed that most of the monsters on this list do one of two things: trick complacent players, or take something away. In the latter category, there is nothing more terrifying to a D&D player than the threat of taking away his experience points. XP determines almost every aspect of a character's power, including hit points, spells and other status effects. So guess what wights, vampires and succubi have in common? Besides being undead, they have the Energy Drain ability which can destroy a massive amount of XP. As mentioned before, even more than gold, XP is the unofficial way players keep score; if they lose what they worked so hard to acquire, and are forced to kill another hundred kobolds in order to graduate from fifth to sixth level… well, it's a fate worse than death for many players. Literally, because if your character dies and is resurrected, they usually end up at the same level. By the way, the most obnoxious of the three undead monsters is likely the succubus. Mainly because when your characters fight vampires and wights, you don't have to keep making saving throws to not try and have sex with them.