Exploring large cities and towns in Dungeons & Dragons, engaging in local politics, meeting various NPCs, and learning their stories, can be exciting aspects of the game. Players enjoy the feeling of being in a living and dynamic world, and nothing can be more dynamic than a sprawling city.
Urban areas can be the scene for confrontations with criminals, assassins, powerful guilds, corrupt politicians, or evil wizards. But only encountering humanoids can become repetitive in an urban game. D&D is filled with fantastical creatures and monsters, and many of them can fit into an urban setting to shake things up from time to time.
10 Cranium Rat
Smaller beasts and pests such as rats are a natural fit for urban settings, and swarms of rats and giant rats can make for a memorable challenge against low-level parties. But there are special variations of these creatures that can be quite creepy and even a decent challenge for higher-level characters.
Cranium rats are beasts that have been experienced on and affected by mind flayers. They are intelligent, they have psychic powers, and can even share their minds to cast powerful spells such as dominate monster. Facing a large powerful monster and realizing a swarm of rats was puppeteering it the whole time, can be a memorable adventure for your players.
9 Stirge
Small insects, especially mosquitos, are one of the most annoying parts of urban life. And like anything else, in the fantasy world of D&D, we can kick everything up a notch. Stirges might seem harmless for powerful characters, but are good at what they do; being a pain to deal with.
These tiny beasts are like mosquitos on steroids. They only have two hit points, but with a relatively high armor class, and an attack that will attach them to the target and drain their life each turn, your players can easily be annoyed enough to blow up a few buildings just to get rid of them!
8 Wererat
Lycanthropy is a fascinating curse in any fantasy setting, and D&D offers many types of lycanthropy from the iconic werewolves to the lesser-known sneaky wererats. While most lycanthropes will be ousted from society and live in the wilderness, wererats' tribal nature and their inherent skill in stealth, make them suitable inhabitants of sewers and underground layers of an urban area.
Wererats are not specifically strong, but they are smart, and they can organize and take over the criminal operations of a city. A thieves' guild made up exclusively of wererats can make a unique and memorable faction in your game.
7 Skulk
There's a rumor going around the town. Small children wake their parents up in the middle of the night, terrified of seemingly invisible monsters. Perhaps it's just the kids' imaginations going wild, but the stories sound way too much alike for it to be just a coincidence.
Skulks are one of the creepiest monsters to include in your game and add a sprinkle of horror to your cityscapes. These stealthy monstrosities can only be seen by young children or through their reflection in mirrors. Skulks are not particularly strong, but tracking and hunting them can be pretty challenging for any party.
6 Golem
Cities are the pinnacle of technology and human achievement, and one of the best ways to reflect that into your D&D game is by using magical constructs. These man-made creatures can be used as guardians, entertainment, or even menaces to the citizens, and your player can form many small adventures around them.
There are many types of golem depending on the materials that were used in creating them, and each one has certain strengths and weaknesses. Clay, stone, or iron golems can be used as bodyguards or security in certain locations of your world, or even the grotesque flesh golems can be found in the lair of an evil necromancer who's hiding in the city.
5 Mimic
Golems can be intimidating creatures that powerful NPCs utilize for their protection, but the more insidious individuals might go a level beyond and hide their protectors in plain sight, disguised as furniture and everyday objects.
Mimics are evil creations, luring pure adventurers towards chests or containers, and strike when they least expect it. Combine them with some other animated objects and put them in the house of powerful evil NPCs, and your players will hate them even more when they are done getting through all their defenses.
4 Doppelganger
If you want your players to not trust any of your NPCs ever again, then include a doppelganger as a villain in one of your campaigns! But in all seriousness, these tricky bastards are perfect inclusion for urban settings. They can turn themselves into any other humanoid and lie and manipulate to get their way.
Discovering and hunting down a doppelganger can take multiple sessions, tens of different social and combat encounters, and introduce your players to the stories and politics between important characters in your world. Just don't overuse them, so your players can still trust and make allies with some NPCs!
3 Vampire
Vampires are a staple of fantasy, and there are grand adventures built around them as villains. But they don't always need to be the ultimate villain in some domain of dread. You can have vampires as characters in your cities and have them be possible enemies or even allies for your players.
These powerful undead monsters can blend in really well in some towns and cities, and introduce interesting adventures and stories in an urban setting. Small gothic towns are the perfect setting for vampires, and working your way through a vampires minions and facing them in a climactic final confrontation, can be really satisfying.
2 False Hydra
There is a lot homebrew content available for Dungeons & Dragons 5e, but perhaps one of the most popular monsters ever created by the community, is the false hydra. There are many versions of this homebrew monsters, and many ways to include it in your campaign, but once you know how to run a false hydra in your game, you can create a challenging and memorable journey for the players.
False hydras are all the more intimidating when they set shop in a populated area. They can charm and trick others, affect memories of people in their vicinity, and make tracking them down almost impossible. Tracking and hunting a false hydra can be a short campaign in itself, and within a large city, there is no limit on intricate and detailed stories that you can tell with this monster.
1 Tarrasque
Not every monster in an urban setting should be threatening it from within. Many creatures can be a danger to a city, from goblins to bandits, from giants to dragons, they can all be a major threat to the safety and the lives of the citizens.
But there is one monster, which is specifically good at destroying cities and razing them to the ground. Everyone knows the legendary tarrasque, as being the highest CR monster in the game. This gargantuan titan can be the final showdown in a long-running campaign, where your players have grown to love the city you created for them, and now they have to defend it against the ultimate danger, an intimidating siege monster.