The Secret Lair

A villain's lair is the safehold, a place to rest and recover, a place to store their loot, their weapons, and the nexus from which their criminal operations are ran. As such, the villain defines the lair, and sometimes, a lair can help define a villain. Conversely, this can be applied to heroes too since Batman has the Batcave, Superman the Fortress of Solitude, and even the Teen-Titans have a T-shaped building, on an island.

The Arctic Base
Located at the north pole, or south pole for the Antarctic Base, this lair is far removed from civilization and the villain is free to perform whatever plans he has. While conditions are less than hospitable, there are no natives, or very few to ask about the strange uber-device, mutated henchmen or super technology going about.

The Underwater Dome
Located beneath the sea, the Underwater Dome has the advantages of isolation and limited access, but can be located in warmer climates, usually accessed by submarine and serviced by a nearby island, usually of the tropical sort. The dome has the weakness of being flooded by the sea if the main dome is compromised.

The Volcano Lair
What villain would be complete without a volcanic lair, situated in an active volcano. Ever-present lava offers quick disposal of ineffective henchmen, and plenty of trap opportunities for the villain. The volcano is also an impressive source of geothermal power, but if safeguard are not taken, a single eruption can consume the lair in molten magma.

The Desert Stronghold
Much like the Arctic base, the Desert Stronghold is remote and requires only limited discretion in it's operation. It has an advantage in that indigenous peoples such as desert nomads and tribal warlords can be accessed for improved defences, provided they are treated moderately well.

The Remote Island
The microcosm, this island is under the full control of the villain and is likely stocked with traps, monsters and beasts of his choosing, and perhaps experimentation, and a local force of militia and thugs. The most important parts of the remote island are the airstrip, and the radio tower, the points of contact with the outside world.

The Underground Dungeon
The staple of some 30 years of adventure gaming, the underground dungeon is a labyrinth of traps, monsters, henchmen, and a final strong point where the villain in confronted. Access is limited, by there is the danger of cave-in, and becoming trapped in a bad place if defences fail.

Large Surface Ship or Submarine
The ocean is a large place, and with a large ship, be it a surface boat or a submarine, a villain can be very elusive. Ships can be equipped with super technology, and can be almost self sufficient with nuclear power, and can be very large.

Airship
More in line with Steampunk and Final Fantasy, the Airship can serve as a mobile lair for a villain, housing troops, weapons, and deploying them. It remains vulnerable to counterattack, so most wise villains will not risk their ship in direct combat, unless there is no alternative.

The Office Building
A towering skyscraper, the office lair offers anonymity as well as access to profession security forces and local law enforcement agencies. This requires a large degree of discretion, as said authorities look down on playing minion for a criminal enterprise. THe adventure of the skyscraper is fighting through a vertical space, though elevator shafts, and stairwells, floor to floor. Stealth and electronics can go a long way in protecting, or penetrating this lair.

The Factory/Warehouse
Located in the industrial sector, few notice strange smells and loud noises, business as usual as most people are concerned. The type of factory/warehouse can play a significant role, as a dynamite factory will require more safety than a bowling ball plant, or concrete factory.

The Hospital/Asylum
For those of the medical persuasion, many operations can be hidden in the red tape and beaurocracy of a large hospital, mental asylum, or private health practice. Mixing a large dose of medical experimentation, unknown drugs, and mental insanity can create a formidable defence.

The Corner Pub
The hang-out of gangsters and mobsters, the corner pub is a place where street wars are planned, drugs deals are organized, and vendettas are began and ended. Variations of the Corner pub include crack and whore houses, seedy motels, and restaurants.

The Casino
Located in an area of legalized gambling, the Casino is a shining bastion of false hope, neon, and promises of fast money. Criminals can launder cash through a casino fast, and like the pub, all sorts of deals can go down. Unfortunately, most law enforcement know about what goes on at the casino, so a degree of secrecy and double-talk is required.

Suburbia
A little slice of Hell, with some effort, a villain can hide in plain sight, living in a large house atop an unknown expansive basement in the middle of a housing subdivision.

The Space Station
Sitting In Earth orbit, the space station is the ultimate high ground. While it is vulnerable to direct attack, most powers will not admit to having anti-satellite or station weaponry, let alone use it. As such, the station has a degree of leeway in it's positioning and use, and giant lasers can be made to look like really big space telescopes.

The Lunar Base
Like the remotes bases, the Lunar base is completely obscured from regular sight. Located on the dark side of the moon, this base is free to do the most blatant of villainy, hidden from every eye on earth.

The Space Ship
Likely a pinnacle of super-science or alien technology, the space ship can be as simple as a mobile space station to as advanced as a FTL capable warship armed with weaponry capable of destroying entire civilizations.

Alien Planet
Sometimes entire worlds go to war with Earth, and as such, their entire planet, be it Mars or Mungo, serves as a lair to the villainous powers that oppose man and Earth. As such, the only limit to what the planet can possess is the imagination.

Mad Scientist's Lab
A staple of sci-fi, the mad scientist's lab is a place of sparking electrodes, errant bolts of lightning. Strange devices give off strange lights and sounds, while the laws of man, nature, and physics are politely told to get bent.

Ghost Town
Complete with many buildings, and no population, this lair has ample hiding capability. More often the hiding place of serial murderers, genetic freaks, and psychopaths, it can also be attached to monster breeding, or a stop point for moving illegal goods.

Summer Camp
No one would expect the evil that goes on behind the smiling happy faces at Camp Crystal La... river. As with the ghost town, more the venue of murdering butchers, but could be used as a place no one would look for a villain. there are the old cabins that have been closed for years, and the such and such facility that used to be used for mountain climbing.

Nod
As in the land of Nod, the realm of dreams. A dream stalking villain will be able to make his lair from the dark fantasies of his victims, using their own fears as his best defences.

Hell
Demons are some of the most nefarious, and more often poorly done, villains. As such, they wont have lairs in buildings, but will have citadels of brass, hung with corpses on a layer of hell surrounded by pits of flame. Only the most demented of heroes would attempt to storm the gates of hell...or try to sneak in.

Pocket Dimension
A surreal piece of non-Euclidian spatial geometry, a pocket dimension is a place that exists at the whim of it's creator, most likely a powerful magic user, demi-god, or alien race. It has the advantages of Hell, but lacks the same magnitude of firepower.

Hacker's Den
located in cyberspace, this VR lair is a hideout for online activities, and can only be reached by a similar VR attack. Villains and heroes fight out highly symbolic battles via virtual reality, while their bodies are left sitting, plugged into a computer.

The Old Castle
Suitable for many settings (spy espionage in the old country, super magi villain, etc) the most famous castle villains are the old hoary vampires and their cabals of blood sucking progeny. The place is old, the walls are thick, and help is a long way away. The wolves and bats are close, and they are hungry.

Pyramid
While also possible for an alien-new age super technology lair, the Pyramid has always been the refuge and fortress of the mummy, be it a shambling horror that can be outrun with a brisk walk, or the modern mummy who is undead but appears perfectly human.

Abandoned Church
Many undead have a sense of irony, and often entreat old churches as their lairs when they are on the move or away from their home grounds. And yes, when a church moves away from a location, they de-consecrate the grounds, so a vampire could once again step foot there.

Cemetery
The haunt of young vampires, ghouls, and cannibals, the graveyard mausoleum is a battlefield waiting to happen, with rows and rows of tombstones, beep crypts, and the like.