In Hollow Fields, underachieving students are sent to detention in "The Windmill". No-one who goes in ever comes out again. Which is because the teachers are using the children sent there as test subjects for a Grand Theft Me experiment. They sort of... Break... In the process.
Mahoraba has Shirogane's own Room 101 inside her classroom for students who misbehave in class or failed to do homework. When not in her classroom, she might borrow some random room for dealing punishments to her students. Played for laughs, misbehaving students are just heard screaming by other students and comes out pale as a ghost with no one ever willing to say what really goes on behind those doors.
20th Century Boys: People who resist being brainwashed at Friend Land (which is already bad enough) are sent for more advanced treatment to Friend World, which is never actually described.
Fullmetal Alchemist has the Fifth Laboratory, where the government's human experimentation takes place.
One Piece has Impel Down's Level 6 which the general public doesn't even know about, where society's very worse are kept pending execution and are meant to be forgotten and erased from history itself.
Fables has a group dedicated to removing the fable characters from memory. One of their punishments for fables who get out of line is what looks like a pit. Apparently being inside causes people to simply forget your existence, which for a fable can mean they simply fade from existence (Paul Bunyan was reduced to a midget after multiple trips).
In the classic (Earth 2) Batman story "The Autobiography of Bruce Wayne", the Scarecrow crashes a wedding that Bruce is attending, and hits the congregation with fear gas, causing everyone to relive their worst fears. When Batman suddenly sees his allies (Robin, Batgirl, Commissioner Gordon, Superman) disappear before his eyes, Scarecrow actually mentions this trope by name: "So, Batman, your greatest fear, your Room 101, is autophobia!"
In Ted Rall's 2024, when Winston is arrested, he's forced to watch Channel 101, which is showing an unbearably boring documentary about rats.
The Sinestro Corps has small capsules like these called fear lodges, since as Green Lanterns power their rings through willpower, Sinestros can power their rings through their own fear, so they face their own worst fear so that their rings can collect it.
Michael Radford's film adaptation of 1984 successfully translated how much Nightmare Fuel Room 101 can be.
"Ward E" from the made for TV movie The Stranger (which was later made into an MST3K episode.)
The interdimensional gateway drive used in the 1997 film Event Horizon. This gateway was an interdimensional jump drive that could travel instantaneously to any part of the universe, unfortunately, the ship would travel through a parallel dimension analogous to Hell.
Room 217 in Stephen King's original novel. Why the change? The hotel used for filming the exteriors had a real Room 217, and the owners were afraid no one would stay there after seeing the film.
V for Vendetta, no one knows what happens to the people who are black-bagged...except of course for the ones who enact said black-bagging. And V, who escaped, and Evey, who was put into a fake interrogation by V.
While never specifically revealed, there is some speculation that the cube in the Cube movie series is one of these. Even if you manage to live through the deadly deathtraps of death, the massive psychological horror experienced within might make you wish you hadn't. And that's only if the people outside the cube don't immediately kill you.
In House at the End of the Street, The number of the prison cell Ryan ends up in is 101. It's implied that he is being tortured by the worst recollections of his life (though as a result of his own mental illness rather than outside interference)- and there are many.
In the The Kentucky Fried Movie parody "A Fistful of Yen," the villain sentences a spy with the most evil punishment imaginable. "Take him to Detroit." "No! Not Detroit!!! NOOOOOOOOOOOOOOOOOOO!!!'
In Robot Holocaust, we have "The Room Of Questions" & "The Tortures Of The Damned".
1984. Trope Namer. Winston has an extreme phobia of rats, ever since he was a young boy. The culmination of his stay within the Ministry of Love, and the chilling climax of the novel's plot, involves him finally being sent to Room 101 where they have a rather unique helmet-cage apparatus waiting for him. Rats are put in one end, his head in the other, and the barriers between his face and the feral rodents are removed one by one until he surrenders; That's not to say "pleads for mercy" or "admits defeat", he has to fully surrender to Big Brother by compromising the last shred of integrity and humanity he's been clinging to, by begging them to inflict this terrible torture on his love interest, Julia, instead of himself.
Rather hilariously, Room 101 was named after a conference room at the BBC, where George Orwell had to sit through boring meetings.
A short parody of 1984, "1984 Has Been Unavoidably Postponed" by Alan Coren, had the Ministry of Love turn out to be short of rats — and Smith wasn't scared of anything else they had to offer. He wound up actually trying to help them find a creature they could torture him with:
"If it's any help, I can't stand moths."
"Moths?!" Esmond screamed. "What do you think we are, ruddy Harrods? We can't get moths for love nor money!"
"Comes in here asking for moths," muttered Esmond's assistant.
Stephen King has used this trope more than once in his stories.
The room 1408 in the short story and movie adaptation of the same name.
In The Shining, Room 217 (Room 237 in the Kubrick version) serves the same basic purpose. Danny Torrance initially surmises that certain areas of the Overlook Hotel are just as dangerous as Room 217 and should be avoided.
In Carrie (and its film adaptations), Margaret has a small, cramped closet in her house filled with religious paraphernalia. She locks her daughter Carrie in there to pray for hours on end whenever she so much as takes a tiny step out of line. In the '02 version, though, Carrie manages to make it into a refuge of sorts from Margaret's insanity, hiding a stash of fashion and gossip magazines in there. The '76 version also has Carrie hiding there with Margaret's dead body as her house burns down.
The "Objective Room" in That Hideous Strength by C. S. Lewis is a sort of mental torture. At a glance, it's an unremarkable room, but the closer you look, especially at the pictures on the walls, the more unpleasant it gets.
Subverted in The Restaurant at the End of the Universe - the Total Perspective Vortex is a machine that causes the soul of whomever gets put into it to commit suicide by showing them how insignificant they are in the universe, but when Zaphod Beeblebrox goes in, it turns out that it merely reveals he's the most important thing in the Universe. This is later attributed to this all occurring in a universe specially created for him, where he truly was the most important person in the universe (go... read the book).
At any rate, he's pissed off enough at Zarniwoop for first abducting him and then bursting his bubble about how he survived the Vortex that he eventually slugs him.
In Poul Anderson's "Sam Hall," the story opens with the protagonist's nephew being arrested and sent to a Room101; the protagonist must hide that they were related.
The Pilo Family Circus has its own Funhouse, a place that even other circus employees avoid, as it's the home of the Matter Manipulator, a flesh-sculpting magician responsible for the creation of the Freakshow. Carnies are sent there as punishment for suitably unpleasant crimes, and visitors to the show that actually enter are never seen again. The only example we see of a victim of the Matter Manipulator besides the freaks is Winston the Clown, who has the flesh of his stomach ripped out and replaced with hot coals.
In the novel Hell House, the whole mansion qualifies, but over it all seems to be the ballroom, to the point Ben Fischer makes it a point to try avoiding it.
The book The Mysterious Benedict Society has the Waiting Room: so horrible that even those who have never been there cringe in fear of it. one of the main characters gets sent there, and it's just a room full of mud and insects; nevertheless, he is nearly broken by it. Later, Milligan gets captured and sent to it and it turns out to work to the party's advantage. He is able to hold his breath and sink down below the mud and then escape.
Crowden, the big bad of Witchfinder: dawn of the demontide, has a demonic cabinet, into which he places people to be tortured. One incredibly unlucky victim had to spend a month inside it.
Dungeon Number One in Magyk. It is essentially a huge chimney-like pit full of rancid water that drowns most of its inhabitants...if they survived the fall, that is.
In Shades of Grey, people whose merit score dips down low enough get sent to Reboot, where they supposedly are retrained to fit into society. It turns out to just be an 'abandoned' town with a town hall painted with a color that kills you.
The danish fantasy series The Shamer Chronicles featured a room that was covered head to toe in carvings of faces that would whisper the worst things you could imagine to you - remind you of horrible things you have done or play on your insecurities until you were driven mad.
In the Wheel of Time series, the Aes Sedai have one of these underground in Tar Valon. Thieves brave enough to try to rob the place get sent there, and are quietly released the next morning, apparently unharmed but never trying that again. We find out later what it is: You're strapped to a block and the local magic really does give you immersive hallucinations of your worst fears.
In the novel Unwind by Neal Shusterman, the main characters are running from the law because they are scheduled for unwinding. The room where the unwinding takes place is one of these, except everyone knows exactly what goes on, just not how.
In The Dream Catcher by Monica Hughes, about a society of telepaths in a domed city, misfit Ruth is sent to The Black Hole, a room with a terrifying reputation for stories of people who'd be driven mad from just a few minutes inside it. Subverted when, it turns out all it does is block telepathy. Most telepaths can't handle it, but Ruth actually finds the place pretty relaxing, and the door wasn't even locked. It was actually a test to see if she was the type of person who could survive without being connected to the telepathic community.
The house where the narrator is kept in The Yellow Wallpaper. Justified, as it used to be a Bedlam House. (And in a way, it's still being used as such because she is there to recover from hysteria. Needless to say, her being kept in a house (and especially her bedroom) that she thinks could be haunted does not help her.
Animorphs drops some mentions to Visser 3's personal torture chamber aboard his Blade Ship. For his underlings even death from starvation is much more preferable than ending up in there.
One strange example appears in the Goosebumps short story "The Chalk Closet." At a certain school, students who misbehave are sent to the closet, where they are forced to listen to the sound of Nails on a Blackboard for eternity.
The humorous BBC chat show Room 101 where a celebrity comes on to talk about their most hated things, which can and will include anything and everything, whereby they make a case for their hatred and if successful, the item is dumped into Room 101 itself.
On an additional note, the most hated thing is apparently packaging, as it's been brought up on the show seven times, more than anything else.
Room 17 in the Babylon 5 episode Intersections in Real Time.
Beautifully subverted by the Dangerously Genre Savvy interrogators themselves: It is just a threat meant to use that trope. Room 17 does not exist, it is merely a way to unbalance the subject before standard interrogation and brain washing techniques resume, while robbing them of any hope for a quick death. The real horror of Room 17 is simply that there is no end, no exit, no hope.
Room 9 from season 2 of Heroes. Maury's apartment where Matt Parkman and Nathan Petrelli are trapped within Maury's illusions of a twisted alternate of the S1 "Bomb" Future.
The Attic, on Dollhouse. We don't see what it actually does until late in season 2, but it's mentioned well in advance...
Topher: You know that feeling when you have a name on the tip of your tongue? Well...that's what it's like. For every thought you never have.
The red bag on British sitcom Ideal. To put it in perspective, gangster Psycho Paul was said to have 'cried like a little girl' after looking inside it, and even Ax-Crazy hitman Cartoonhead is scared of it.
The Professionals. Bodie and Doyle lampshade this trope after capturing a hitman who refuses to say who employed him. So they take the hitman to the business of an East End gangster whose brother he killed and handcuff him to a lamppost outside. "Oh he won't kill him. But he'll wish he had." The hitman wisely decides to talk.
A terrorist played by Quentin Tarantino in Alias had a portable version of Room 101; "The Box," which he kept threatening to open if he didn't get answers. It turns out it was full of needles spiked with something that would cause a terrible burning sensation that he'd jam into the fingers of his torture victim; painful, but at the same time, not exactly up to the massive hype he built up.
Roswell: The FBI Special Unit tortured Max inside "The White Room".
La Femme Nikita: Section 1 had a cell known as The White Room, where captured hostiles were routinely subject to torture, interrogation and "Cancellation".
In The Sarah Connor Chronicles, Skynet's machines operate one of these in the basement of an abandoned house in the wasteland. Precisely what happens down there is never made clear, but Derek Reese is subjected to whatever it was they did down there. Creepily enough, coming from said room is the sound of a piano playing a particular song by Chopin - the same song is playing an episode later while Cameron is ballet dancing, and later on in the series it is revealed that Allison Young, the girl whose face and identity Cameron stole, had a mother who liked that same song. Coupled with Derek Reese's familiarity of and hatred toward Cameron, there is a strong implication that she's tied to this particular instance of Room 101.
Played absolutely straight in The God Complex, featuring a space prison resembling a hotel. Each inmate has a room which contains their worst fears, and a Minotaur-like monster that feeds on the inmates after being subjected to them. The Doctor thinks the Minotaur is feeding on their fear, but it is revealed the purpose of the rooms is to force the inmates to reveal their faith in someone or something to protect them, and that is what the monster manipulates and feeds on.
There's also Floor 500 on Satellite Five, from the episodes The Long Game and Bad Wolf. Slightly subverted at first, since everyone wanted to be promoted there, but eventually revealed to be a place of horrors.
There is a stealthy nod to the trope in the Star Trek: The Next Generation episode "Coming of Age". Wesley Crusher is taking a test to enter Starfleet Academy, and the last test is a personalized "psych test" meant to pit the candidate against their greatest fear (Altough Wesley is passed up for admission this time around, he is commended for handling his test well). When he is summoned for the beginning of his final test, he is summoned into "Room 101".
The Trope Namer example is mocked in an episode of The Goon Show called "Nineteen Eighty-Five!": Protagonist Ned Seagoon is locked in a room and forced to listen to a recording... of himself, singing (Harry Seacombe, actor for Neddy Seagoon, was in fact a very accomplished opera singer).
Also in That Mitchell and Webb Sound, in a sketch depicting the problems of working in Room 102. Especially when those noisy buggers next door are torturing someone whose worst fear is a whale with the face of his old French teacher. Also brings up the problem of what happens when people start getting wise to how Room 101 works. Seems a suspiciously large number of people have suddenly developed a fear of sexual intimacy...
Unknown Armies has the Rooms of Renunciation, pocket dimensions where someone the universe doesn't like gets shut in until they come out different. How different? Depends on the room...
Exalted has the Monstrances of Celestial Portion, which is like this to the Solar Exalted. Yes, even the immortal god-kings of Creation have something that makes them scream in fright. What are they? The Deathlords traded some favors to the Yozis to create an engine that would invert a Solar Exaltation's nature and make them serve the cause of death, turning those bestowed with it into the Abyssal Exalted. And if a Solar's stuck in one of them... well, it ain't pretty. Hell, a Solar can't even look at one without feeling sick.
Likewise, Werewolf: The Apocalypse has the Spiral labyrinth, which werewolves are forced to walk to turn them into Black Spiral Dancers (except in one notorious case where that didn't work, and Celeste Walks-The-Spiral-Backwards destroyed the labyrinth instead). Mage: The Ascension works on reincarnation of every mage's avatar, but has a horrid ritual to destroy avatars. And Vampire: The Masquerade contains a few fates worse than death because all the vampires are, of course, already dead.
Also from Mage, the Cauls, which invert a mage's avatar, turning them into one of the Nephandi, mages dedicated to corruption and destruction. For that extra nasty twist, when a Nephandi dies, it's possible for their reincarnation to be born with their past life's twisted avatar - corrupted from birth.
Warhammer 40,000 brings us Commoragh, home of the Dark Eldar-a planet-sized extradimensional City 101, which is as horrible as it sounds, since its residents live on squick.
And then, anything there is owned by the Inquisition.
Dark Elven cities in the Fantasy Battle setting are just as bad.
Dr. Dominiani has a whole asylum floor full of these in his domain of Ravenloft, which he uses to systematically drive people mad.
In Kult, The Abyss, a great chasm where Demiurge's citadel once was. Only Astaroth has ever been known to get in there and return, but only barely alive. And he refuses to speak about anything inside that place.
Urinetown in Urinetown has this reputation. It turns out, though, that there is no Urinetown; those who are sent there are just thrown off a building to their deaths.
The Punishment Sphere facility from Sid Meierís Alpha Centauri. Drones—the uneducated, disaffected unskilled worker class — will never, ever riot if you have one of these. It's never explained what's done (though according to the sound file that plays when you build it, one man who was tough enough to take it quickly broke when his wife was put in...), but whatever goes inside must be really, really, really nasty, because building it also halves that city's scientific research output and prevents citizens from becoming Talents, the educated and creative class, which also prevents that base from ever entering an intellectual Golden Age.
The game also references "nerve stapling" as the dictatorial method of quashing Drone Riots. Nerve stapling is implied to lobotomize its victims into mindless workers. Not necessarily gruesome per se, but certainly a flagrant violation of human rights nonetheless (and a horrific punishment by any measure).
In fact, using the Nerve Staple option to "calm" your populace is considered an Atrocity by the other factions, and will temporarily do horrible, horrible things to your economy as everyone stops trading with you for several turns (which can be devastating for any faction that relies on trade routes and external income, as in the other Civ games) and you get temporarily chucked off the Council.
If you manage to get the UN Charter repealed by the Council, then it is no longer considered an atrocity to nerve-staple people or use nerve gas on civilians. Planet busters are still a no-no.
In Dragon Sun by Michael Ely, nerve stapling is developed by Yang's scientists in order to more effectively control his population and create a nigh-unstoppable army. When the others find out about it, they are utterly horrified and put Yang in jail for life. The victims they find have some sort of electrodes in their heads used to induce intense pain.
When a rival faction is defeated by the player, a short clip (one for male, female, and Progenitor) shows that leader in a punishment sphere.
Killer7 has the Forbidden Room, which may or may not be the source of the horrific screaming and moaning heard in the building throughout the game. Eventually it's revealed to contain Kun Lan and Harman playing chess, the entities who rewrote Garcian's identity, shaping him into a pawn in their endless metaphysical battle.
Echo Bazaar has a Room 101 in the evil hellhole that is the Orphanage It actually contains nothing worse than mops, its a store room.
In BlazBlue, this is what can be described as Relius Clover's Astral Finish: Sending people to the Room 101 that is his lab.
Parodied in Invader Zim, where Zim opens a wormhole and had several options of places he could choose from to send his rival Dib. Out of all the unpleasant places he could send Dib and the rest of the class, he chooses... A ROOM... WITH A MOOSE! (His other options included a dimension of pure itchy, and another of pure dookie.)