What Monster Stalks This City?

Traditionally cities are usually places to rest and resupply between adventures, rather than places to have adventures.  As someone who cut his teeth playing Shadowrun, I don't like this– I think the potential for cities to be adventure locations has been sorely under-appreciated.

The obvious adventure hooks for cities involve gangs, political intrigue, burglary, business espionage/sabotage, and other human-centric plots.  But cities can have monsters too; you just have to think about what kinds of monsters could plausibly hide in a city.

1– Vampire

Stats as per the monster manual of your choice, but this has to be the human-looking kind of vampire.  Has to feed either every night (not dangerous to victims), every other night (dangerous but probably not lethal for victims), or once a week (if completely draining victims of blood).  Probably has a consistent M.O., like it almost always feeds on prostitutes, or drunkards, or muggers, or sailors.  Will have 1d4 mind-controlled slaves to watch over it and do its errands during the day.

2– Ghost

Haunts a whole neighborhood, not a single house.  Incorporeal and immune to normal weapons, and very tough overall because it can vanish into the ethereal if wounded.  Getting rid of it requires either very powerful magic or figuring out why it is a ghost and fulfilling some specific condition, such as bringing its killer to justice.

3– Serial Killer

Just a normal human, physically anyway.  Likely has a consistent M.O., and almost certainly has a specific "type" that they go for.  Like, Ted Bundy always picked women who parted their hair down the middle.  Has no physical need to kill, so the time between murders is more a matter of willpower and convenience.  Will tend to become more brazen over time.

4– Abhorrer

As per Fire on the Velvet Horizon.  Since that book doesn't provide stats, try this: It has 4 HD to begin with.  It gains one HD every (current HD squared) weeks, assuming nothing happens to help or hinder it; gaining HD is a matter of accumulating wealth and social and political influence, mainly, but it also grows a bit bigger as its HD go up.

Its "no breaking laws of social conventions" effect works on anyone within line of sight, and also passes through barriers within a radius of HD squared times 20 feet.  After a few years, its power can effectively prevent anyone from committing a crime anywhere in the city.

Assuming the abhorrer becomes well-known throughout the entire city before it dies, its death will trigger a sudden, massive city-wide crime wave, particularly if it is killed via a scheduled execution. Everyone who wants to commit a crime will simply wait for the moment of its death to do so.  Hopefully the party will be smart enough to foresee this.

5– False Hydra

As per this article.

6– Pack of Morlocks

They live underground, in the sewer, caverns or old mines beneath the city.  There are 3d10 of them.  They venture to the surface to scavenge for supplies, killing only when they need to, either to get supplies or prevent someone who saw them from telling people about them.

I've seen a few versions or morlocks; I like the ones in Esoteric Enterprises best, although you may have to adjust the way they work a bit to match your game's setting and mechanics.

7– A Cult

Maybe it's kidnapping people to sacrifice them, or maybe the leader is just luring vulnerable young people into his orbit so he can build some dumb harem.  Probably a bit of both, like the Manson Family. Then again, maybe their god is real.  Maybe it's a serious Great Old One cult masquerading as a rather frivolous sex cult.

The party could learn about this by investigating a ritual murder, a person who's been kidnapped, or a person who simply disappeared when they joined the cult.

8– Dopplegangers

They're moving in slowly, one or two at a time, replacing established locals.  They started out at the bottom of society, taking the places of a few bums and laborers with few social ties.  From there they worked their way up, killing and replacing servants and craftsmen, then minor merchants.  Now they're moving on to wealthy merchants and minor nobles.  Their ultimate goal is to completely replace the city's ruling class.

The party will most likely learn about this from a merchant or noble who notices that a friend of theirs no longer seems to remember people or events they should be familiar with, and hires the party to investigate.  Plot twist: while they're investigating, the person who originally hired them gets replaced by a doppleganger too.