Also known as a "house of ill repute", a Den of Iniquity is typically a room, auditorium, or stadium in the Evil Overlord's Evil Tower of Ominousness or Island Base where all sorts of sin and wrongdoing takes place. Although towers are in short supply nowadays, if the Big Bad happens to make and/or enforce the laws they might have one in their mansion (but explaining them to less debauched guests might be tricky).
The level of debauchery will vary according to the setting in question; family-friendly stories might make it a lounge for the Mooks to gamble, get drunk, and brawl (not necessarily in that order), while Darker and Edgier works might go for rape, torture, and blood sports.
The Den of Iniquity is often a hangout for the Mooks or Faceless Goons who need something to keep them entertained when they're off-duty. On the other hand, whether the Big Bad or The Dragon indulges in the debauchery depends on where they stand on the Sliding Scale of Antagonist Vileness.
Often populated with the Paid Harem and Bodyguard Babes. The Den Of Iniquity isn't restricted to "evil" characters (as Miss Kitty can usually attest), but most heroes will simply find it beneath them.
- Babel Tower from the beginning of the second season of Code Geass. Gambling, blood-sports, waitresses in bunny-girl outfit... and particularly rich and influential guests could indulge in 'rabbit-hunts'. It's never specified exactly what that means for the caught 'bunnies', but one can make reasonable guesses. Unfortunately for one mafia-boss, however, he happened to catch a Killer Rabbit...
- The Amazon Trio of Sailor Moon Super S has a more subdued example in the form of a bar with a lone saxophone playing to lounge in-between missions.
- In L'épée de cistal, there is one that is also a "stock exchange of sins": the minions shout the name of one of the seven Deadly Sins, and by that means influence people all around the would to commit those sins.
- Old Town in Sin City is an entire city district of iniquity, what a Red Light District would be if it was openly owned by the ones providing the "entertainment".
- A very family-friendly version of this appears in The Smurfs comic book story "The Gambler Smurfs", as Papa Smurf discovers that the Smurfs have set up a private gambling room in the village.
- Hellblazer: In "Mortification of the Flesh", we learn that the Vatican has one, specifically, a room enchanted to be hidden from the eyes of God so that whatever is done in there isn't a sin. Built by Pope Alexander VI, who you may know better as Rodrigo Borgia. And the room certainly lives up to its reputation, having seen theft, fornication, murder, demon summoning... in that chapter alone.
- In Toy Story 3, there is a humorous example of a bunch of 'bad' toys hanging around in a vending machine, betting with Monopoly money and triple A batteries. They use a "Speak-And-Say" toy instead of a roulette table.
- The opening song in Aladdin (yes, the Disney version) has the protagonist in a place with some scantily clad harem girls, who clearly know who he is. (Far from the only example of Getting Crap Past the Radar here.)
- Return of the Jedi has the audience chamber in Jabba's Palace, with musicians, live dancers, chained slave girls, and a rancor pit where unsuspecting victims were thrown in for the audience's amusement.
- Thulsa Doom's orgy chamber in Conan the Barbarian (1982). Goes from creepy to horrifying when you notice exactly what's on the menu in there.
Subotai: So this is paradise.
- Xerxes' royal pavilion in 300, filled with drugged courtiers and all forms of sex. And pot-smoking goat-headed servants.
- Tony Stark's jet is a PG-rated version in Iron Man, complete with drinks, stripper pole and lascivious dancers.
- The hideout of the Foot Clan in Teenage Mutant Ninja Turtles (1990) contains a room where underage teens smoke and gamble.
- Tiberius's mansion in Caligula takes this Up to Eleven.
- Herod's throne room in The Young Messiah is filled with dancing girls, witches, and lizard eaters.
- In Kim Newman's The Hound Of The Durbervilles, Professor Moriarty has his apartment and criminal base in a building which has as its first floor a brothel, and his number two, Colonel Moran, often indulges himself with the "other employees." Moriarty himself seems to have no sex drive.
- The term "Den Of Iniquity" first appears in Robert E. Howard's story "Texas John Alden".
- In the book Third And Indiana, several of Diablo's hideouts are dens of iniquity.
- Ctuchik's tower in The Belgariad is described as having several levels, one for each of his "exotic perversions". They include torture, wealth and one which the hero isn't allowed to enter
- In the Star Trek: A Time to...... series, The pirates at Rashanar have one inside a derelict spaceship.
- Qibbu's Hut from the Republic Commando Series of books.
- In The Dresden Files, the psychic 'vampires' of the White Court maintain Club Zero, a 'club' where pretty much anything goes: sadomasochism, drug use, every alignment of sexual activity, gluttony, booze of any sort, anything you want is available, and doesn't even cost that much in terms of money or the like. As Harry recognizes, you can find anything you want in Club Zero...except fulfillment or meaning or love.
- In Being a Green Mother, we find that Satan runs Mock Hell, where all types of sin can be indulged in, for "merely" a percentage of evil on your soul. Of course, when you get over 50%, you go to Hell for real. And it's no picnic. Of course, Satan being Satan, the pleasures aren't real, but the evil on the soul is.
- Anne Bishop's Ephemera novels have a Landscape called the Den of Iniquity. Described as a "carnal carnival" it's actually not a bad place, and the villains aren't welcome there.
- Appears in The Eye of Argon as part of its massive collection of stock fantasy cliches.
- In Please Don't Tell My Parents I'm a Supervillain, Chinatown is a popular hangout for villains. Heroes stay away by truce.
- In The Letters From Nicodemus Herod is throwing a birthday party. Yes, that Herod. Booze pours like rain and shameless women dance all night long in the Den of Iniquity Herod's palace becomes.
- The Handmaid's Tale has Jezebel's, one of the few establishments left in Gilead where prostitution is permitted, but only to entertain the men. It passes itself off as a Smoky Gentlemen's Club to make itself seem respectable in the face of the country's own moral hypocrisy as a supposedly "God-fearing" theocratic state.
- Captain Pike's fantasy-planet in the original Star Trek's "The Cage."
- Tiberius' mansion in I, Claudius has one of these. The historical Tiberius, on the other hand, did not want and did not need one of these: an antisocial prick but able administrator, he preferred to spend his time mostly alone in his pleasure palace on the island of Capri, and according to Roman historian Suetonius, "indulging his pedophilic predilections" in private. Although later research showed that Tiberius went to Capri mostly because he wanted to hide from assassins and read in peace.
- Supernatural sees Dean haul the angel Castiel to a brothel the night before said angel expects to perish in a confrontation with the archangel Raphael. The incredibly straightlaced Castiel reacts predictably.
Castiel: This is a den of iniquity. I should not be here.
Dean: Dude, you full-on rebelled against Heaven. Iniquity is one of the perks.
- It takes a hilarious turn when Castiel gets invited into a backroom with one of the girls. Moments later she runs out of the room shouting obscenities at him. Cas apparently read her mind, and casually told her it wasn't her fault her dad left her family when she was little. Dean and Cas are forced to leave post-haste when the bouncers show up.
- In Eagleheart, a bizarre bylaw makes it legal to do anything in the sky. Everything goes, up to and including murder. Naturally, a crime baron sets up a blimp as his base of operations where every type of crime is indulged and encouraged (except smoking, because of the hydrogen)
Chris Monsanto: So what you're saying is that everything is legal in the sky, and there's a huge crime blimp floating around? I wonder how I missed that.
- In the Book of Jeremiah (of The Bible), God condemns the Jews for treating His Temple like "a den of robbers" by breaking all the commandments except for "keeping the Sabbath holy" (by implication), declaring that "we are delivered" so that they can continue doing their abominations. (The same description is used by Jesus in the Gospels when He goes into the Temple to clean it out of the marketers and money-changers violating her sanctity — an image made much more vivid in the theatrical and stage productions of Jesus Christ Superstar.) In the apocryphal book of 2nd Maccabees, the Temple is actually reduced to this with the introduction of pagan revelry by Antiochus Epiphanes, including sex workers and roasting abominable meats.
- The Bad Taste Bears figures feature one of these◊.
- Fallout: New Vegas has Gomorrah, run by The Omerta. It also serves as a Minigame Zone.
- The Temple of Depraved in Warriors of Might and Magic. They're mainly demons worshippers and, for some reason, Gnolls and Ogres.
- The Elder Scrolls V: Skyrim has The Ragged Flagon, where the Thieves Guild hang out in-between jobs, located in the Ratway underneath Riften.
- World of Warcraft:
- The Den of Mortal Delights in the Black Temple raid instance in has parks, fluffy pillows, fountains, hookahs, silk curtains, nubile dancing blood elves, succubi and other female demons in stark contrast to the rest of the temple.
- Sunwell Plateau has a zone called the Den of Iniquity but it's empty and wrecked.
- In Talador, part of the city has Legion demons called "Concubines of Lust" and "Nefarious Madams", along with many mortal Legion members. It's pretty obvious what the purpose of the place is.
- Dishonored has the Golden Cat, a pleasure establishment incorporating a brothel, bathhouse, and burlesque parlor, which is regularly visited by the aristocrats of Dunwall.
- Perfect Dark Zero's first mission is set at a Triad nightclub.
- In Splinter Cell: Conviction's co-op campaign, The Mafiya operate a strip club/brothel in a wine cellar beneath the St. Petersburg bathhouse.
- Girl Genius: In a quick flashback Gil is shown someplace Tarvek seems to have considered to be Gil's Den of Iniquity in Paris, though it's implied to have been at some kind of bar, brothel or Opium Den so it wasn't in reality, surrounded by scantly clad women with something rather bong looking mostly cut off at the edge of the panel.
- The Venture Bros. showed a low-key example of this in the fourth season, a room inside the Monarch's cocoon where his minions would quietly gather for drinks on their downtime.
- Another low-key example: in one Kim Possible episode, Ron stumbles upon a room full of Drakken's henchmen sitting around taking a break.