fMRI reading: "99 bottles of beer on the wall, 99 bottles of beer..."
"We are all aware that the senses can be deceived, the eyes fooled. But how can we be sure our senses are not being deceived at any particular time, or even all the time? Might I just be a brain in a tank somewhere, tricked all my life into believing in the events of this world by some insane computer? And does my life gain or lose meaning based on my reaction to such solipsism?" - ProjectPYRRHO,Specimen 46, Vat 7 [Subject termination advised]
The Kedora from Mazinger Z and Great Mazinger. Ken Ishikawa one-shot "The Relic of Evil" revealed that the Mykene controlled his Robeast by grafting the brain of a soldier taught to destroy all no Mykene civilizations into a parasitic organism, and it fused with a robot, giving the Mykene soldier complete control. They would show up later in Shin Mazinger.
Most full cyborg models in Ghost in the Shell allow for the case that holds the brain to be removed and connected to an external life support system. In one episode of Ghost in the Shell: Stand Alone Complex a government official is about to be smuggled out of country by hiding his brain in a suitcase.
Both the anime and manga versions have minor characters described as Jameson-type cyborgs which take this more literally than most. Most full body cyborgs have a body that at least looks human but Jameson-types eschew this with a roughly cubic metal box on wheeled legs with a camera on a stick and a manipulator arm. For extra irony the anime one runs a company that specialises in growing cloned organs for those who don't want cybernetic replacements if injured... and he got the money to found the company by selling all his organs in the first place.
The Magi computers in Neon Genesis Evangelion are powered by human brains However, although the episode mentioned "organic supercomputers" that bear a strong resemblance to a human brain, it's not clear whether they used actual cloned human brain tissue or were just reverse-engineered.
In AKIRA, this is the current state of Akira, together with the rest of his nervous system...until he comes back, that is.
Dragon Ball Z's 2nd movie, World's Strongest, features Dr. Wheelo, who seems to be a brain in a jar. But then turns out to be a brain in a jar in a massive mecha. With guns. And lasers.
Despite being an Anime-version of a Western pulp series, Simon Wright from Captain Future should be mentioned here. He is an archetypical brain in a (highly mobie) jar, with tractor beam and other appendages; and an array of Blinkenlights for a mouth.
It is (briefly) revealed in ROD the TV that the reality-warping effect that causes London to take on elements of fictional works like The War of the Worlds and The Lost World is (at least in part) run by the preserved brains of famous authors.
In the Lupin III movie The Mystery of Mamo, ending spoiler: it turns out the movie's main villain was a gigantic version of this trope all along, and all the "clones" of him running around were all controlled with microchips in their brains that were wirelessly connected to him.
Teitoku Kakine of A Certain Magical Index has been reduced to this after Accelerator horribly dismembers him. It's also forced to create a constant stream of Dark Matter for the use of Academy City's soldiers. He eventually manages to create a new body out of Dark Matter and escape.
Rensa is a cyborg with 40 different brains that can be inserted into her head to animate her. After Touma destroys Rensa, he finds the brains and puts them into cold storage until something can be done about them.
In A Certain Scientific Railgun, Exterior is revealed to be a giant brain in a tube, cultivated from part of Misaki's cerebral cortex. It was intended to allow other people to use the ability Mental Out.
Which even has its own (not tournament-legal) card. The gag, by the way, dates back to at least the February 1998 issue of the long-defunct Duelist magazine, in which Mark Rosewater explains the 'Top Ten Myths About Magic R&D' — the myth about Gleemax is listed as #1, and it's not quite clear from context whether MaRo refers to an actual earlier myth or is just throwing in a red herring on the fly.
The 2000 AD futuristic sports team The Harlem Heroes suffered a crash in their first adventure. One member became a brain in a jar as a result.
Another 2000 AD strip, Bad Company, featured Kano, a patched-together half-mad soldier who believes he carries the human part of his brain in a box. It's really just some random corpse's grey matter to keep him docile; he tends to go a little (more) crazy when he thinks he's lost it.
Doom Patrol villain The Brain in The DCU. In one continuity he finally does manage to get a body—only to die in an explosion a few minutes later, moments before kissing his right hand man, Mallah, to whom he'd just confessed his love for.
Who's a talking French Gorilla. You had a Brain in a jar in a robot being in love with a homosexual talking French Gorilla. Gotta love comics!
More literally in the spinoff oneshot "The Iron Prometheus" starring Badass Normal Lobster Johnson. In order to extract the secrets of the Vril Energy Suit from Professor Gallaragas the villains literally do this to him. Then the villain shoots him. He comes back later as a the Ghostly Advisor to the guy wearing the VES suit.
Atomic Robo has the crazy scientist who isn't just a brain in a jar. He is several brains in several jars, apparently having cloned himself to immortality. Every time his currently active brain dies, a new one "wakes up".
In Avengers: The Initiative, Think Tank is a member of Montana's state superteam, Freedom Force. To all appearances, his head is a brain in a spherical glass case perched atop an otherwise completely normal human body. He's telekinetic and wears a headband and not much else is known about him.
In the ElseworldSuperman & Batman: Generations, Lex Luthor is reduced to a brain in a jar after the Ultra-Humanite hijacks his body in the 1940s. He gets a robot suit powered by Kryptonite, becoming this universe's version of Superman villain Metallo. In Generations 3, he causes even more trouble by helping Darkseid's Parademons set off a bomb that shorts out modern technology, sending humanity into a dark age until they get back on their feet in the 23rd century.
President Rexall of Give Me Liberty becomes one of these after his coma. He even campaigns as such...
During an early 90's Superman story Lex Luthor fakes his suicide and has his brain (along with spine and eyeballs) put in a vat from which it directs its very own transplant to a younger Luthor clone.
In "Operation Friendship", in Tales from the Crypt #41, a genius who felt that he was losing his best friend to said friend's less-intellectual new wife removed about two-thirds of the guy's brain and kept it in a jar with a speaker attachment.
An album of Sillage features this being repeatedly used by an assassin on his marks. After defeating a target, he slices his head open and teleports his brain away in a previously prepared jar. This is intended as a way to both imprison and interrogate them, since most of them are rather powerful and rich people. All of these persons being non-humans of various species, some with a Bizarre Alien Biology like an alien with an X-shaped head and four small brains require quite specific jars.
A background villain in Powers Vol 1 #35 and #36 is a living skull in a jar.
In Empowered, the supervillain Psychoblast has been reduced to a brain in a jar. He apparently still has his powers, as the villain Idea Man comments that he can trigger the apocalypse, but Psychoblast has to be roused from slumber by beaming images into his mind, preferably images of a Hot Librarian.
In The Power He Knows Not Is Voldemort stuck the brain of a mook who failed him in a glass globe attached to an eye and a large number of flytraps. The eye acted as a surveillance system while the plants supplied enough nutrients to keep the whole thing in operation.
In Young Frankenstein Igor was sent to retrieve the brilliant Hans Delbruck's brain from the Brain Depository. Igor drops the jar containing the scientist's brain, and instead takes a different jar marked "ABNORMAL - DO NOT USE". After the monster reveals its true nature, Dr. Frankenstein asks Igor whose brain he put in the body. "Abby someone." "Abby who?" "Abby Normal."
In the German-dubbed version, this became: "I took the brain of a cleric, an abbot (Abt)." - "What abbot?" - "Abt Normal." By the way, as he mentions on the DVD, Mel Brooks had Froderick Fronkensteen Frederick Frankenstein send Igor to fetch Hans Delbruck's brain because that would rhyme with "Mel Brooks' brain". So it is not a reference to the German politician and historian Hans Delbrück (1848-1929), father of the Nobel Prize-winning German-American biophysicist Max Delbrück (1906-1981).
The original RoboCop is apparently a brain-in-a-jar-in-a-robot, with the face additionally transplanted onto the robotic head. (RoboCop 3 states that it's the original face, but the original script contained a removed scene where Murphy's "Terminator-like" skull would be shown.)
RoboCop 2 shows Cain's brain literally in a jar, about to be transferred into a robot. With his eyes still attached, allowing him to see his face that's been cut off of his head.
General Grievious is actually reduced to a brain inside a fully robotic body.
Also, the monks in Jabba the Hutt's temple-turned-hideout. When they need to move around, they can attach their brain-jars to spider-like sentry droids.
The uncle of the two murderous cannibals masquerading as vegetarian chefs in the weird horror-comedy Blood Diner is reduced to one of these (complete with eyeballs). He still orders them around to put together a body for some evil goddess out of all the girls they've killed. We said this was a weird film.
The Conjoiners in Alastair Reynolds's Revelation Space series tend to opt for a brain-in-jar form of treatment when they're very old. However, their "jars" are mobile, crab like devices. The Demarchists also use this for their outer system police; a pilot joins up, his brain and spinal cord is removed and inserted into a small space craft, with a remote controlled drone for them to use when inspecting ships. When they're done with their term, their brain is inserted back into their body.
Mayflies by Kevin O'Donnell
Plus by Joseph McElroy
William and Mary by Roald Dahl. Cold and dominating husband William is dying of cancer, but has his brain and one of his eyes kept alive. It's presumed that his wife, Mary will torment him by doing all the things he forbade her in front of him, now that he's helpless.
A TV version of this short story explicitly shows her doing just this.
The Whisperer in Darkness (1930) by H.P. Lovecraft is the Trope Codifier, in which the alien Mi-Go plant living human brains in cylinders to transport them to other planets, which the human body apparently cannot withstand.
The 2011 film ends with The Reveal that this happened to Albert Wilmarth himself, and the entire story he's been relating as a holographic projection coming from a brain in a can.
Boojum by Elizabeth Bear and Sarah Monette. Space Pirates piloting a Living Ship raid a freighter that turns out to be carrying a cargo of Brain in a Jars in a black market trade with the Mi-Go. The Pirate Girl captain decides to sell them to the Mi-Go herself, only for swarms of them to turn up with lots of additional empty jars...
That Hideous Strength by C.S. Lewis. A whole head this time, with an overgrown brain, plus air tubes to pass "breath" through the vocal cords and mouth allowing it to speak. And artificial drool.
Though it's later revealed that the Head isn't really alive in its own right rather, it was the tool malevolent Energy Beings used to communicate with their pawns.
The Star Wars Expanded Universe, specifically the short story anthology Tales from Jabba's Palace, reveals that the spiderlike droids seen in Jabba's palace in Return of the Jedi are mechanisms used for getting around by a group of monks who have chosen life as brains-in-jars. (You can actually see the jars on the undersides in the film if you know to look for them.)
Bib Fortuna, when a fellow Twi'lek and associate of his was slated to be fed to the Rancor, had the man's brain removed and stuck in one of the spider droids first. Bib believed that without a body Nat was going insane. The epilogue reveals that Bib Fortuna eventually joined him. The X-Wing comics reveal that Bib was still able to plot and get messages out; eventually yet another Twi'lek came to carry Bib off, heaping a lot of verbal abuse and using electric torture on the brain walker in the process. Later the other Twi'lek tried to ditch the walker, but Bib stowed away and, after the other Twi'lek was stabbed, managed to drag him back to the palace and the monks. Cut to the Twi'lek rising out of a bacta tank, and the attendant droid remarking on the loyalty of the brain droid, how it had insisted on having a restraining bolt fitted to it, and that the scars on the Twi'lek's head seemed to indicate a brain transfer. Devious, Bib. For someone with a "weak will", that's rather Magnificent.
Part of a Twi'lek's brain is in his or her headtails, so a Twi'lek brain in a jar looks rather odd.
Galaxy of Fear: The Brain Spiders deals with this too. Jabba found a way to profit off brain spiders by transferring brains around, putting wanted criminal brains in monk or prisoner bodies, putting the displaced brains in jars or spiders, and turning the criminal bodies in for reward. Thanks to an intended monk escaping, one criminal ends up in 13-year-old Tash Arranda's body. He does not like being a girl, and she doesn't like being in a spider. Fortunately, that gets reversed.
Once Jabba dies, the monks went batshit with brain spider-ing, doing it to anyone who stayed in the palace. Most didn't want to, but one criminal, as revealed in the epilogue for "Tales From Jabba's Palace", went willingly because he was tired of living in the heat and he couldn't leave Tatooine.
Also in Star Wars Expanded Universe: In the Tales of the Jedi series, a Jedi Master by the name of Ooroo is a brain-like, methane-breathing alien who must stay in his fishbowl as oxygen is lethal to him. His species, the Celegians, was given a name and some background for RPG; authors never saw a great use for them.
Larry Niven's short story "Becalmed In Hell" has a sans corpus fellow running a probe to the surface of Venus, and contains a Shout-Out to the above book by naming the bodiless chap Donovan.
The first novel based on the Doom videogames had the Legions of Hell actually Hand Waved as genetically engineered scare-tactic bioweapons created by aliens who consist of huge brains in Giant Spider-like mobile carriers.
In Harry Potter and the Order of the Phoenix, the gang runs into a room with several flying brains in jars while fighting their way through the Hall of Mysteries. Ron (who's punch drunk at the time) starts playing with them and they begin to attack everyone...with tentacles made of thoughts. The Department of Mysteries is a very strange place.
Orson Scott Card's Wyrms features talking disembodied heads kept alive by some kind of leech.
Occasionally seen in the Perry Rhodan universe, with both disembodied human brains (though usually those are given robot bodies at the very least) and alien ones — the 'Central Plasma' that governs the mostly-robotic Posbi species is basically one giant protoplasmic brain in a jar. One arc of the series even dealt with the abduction of the titular protagonist's brain into a distant galaxy; an android brain was substituted and operated his body for nefarious purposes while he tried to find his way back. (Good thing the civilizations of said galaxy had their own brain transplant technology as part of their quest to extend life, even if it did contribute to their acute overpopulation issues; so, plenty of disembodied donor brains around there, too.)
The Takeshi Kovacs series by Richard K. Morgan features another twist on the cyberbrain sub-variant of this trope, in the form of "cortical stacks" implanted in every person's brain that basically serve as a mirror backup of the brain in question. Stacks can be transferred to other bodies ("sleeves") at will, transmitted across networks, mounted within VR constructs or simply stored to disk.
Keith Laumer's A Plague of Demons, in which human brains are installed in alien war machines.
Daniel Dennett's short story "Where am I" about a man being separated from his brain, which explores relevant philosophical ideas.
Orson Scott Card once jokingly referred to this as a possible solution to Bean's condition. He also expressed serious revulsion at the idea, so we probably don't have to worry about him following through with it.
(Edmond Hamiton / Mort Weisinger / Oscar J. Friend)'s Simmon Wright of the Captain Future universe almost is an archetypical brain in a jar.
E. C. Tubb's Dumarest of Terra series have the evil Cyclan led by an interconnected set of ancient brains in jars. They need a secret process entrusted to Dumarest to stop the brains from going mad.
The space-faring slavers from Vernor Vinge's Tatja Grimm's World kidnap people, remove their brains and then fit them to a computer that suppresses their personality without totally trashing their intellect. The result has computer speed and power with some human intuition and intelligence, forming a useful Wetware CPU.
Left Brain, who replaces Eddie the Heart of Gold computer in And Another Thing..., is actually Zaphod's second head, put in a jar and connected to the ship.
An Igor in Making Money cites the invention of a "living brain extractor" as proof of a famous scientist's great achievements. Also as proof the inventor was not mad, but what else can be expected of an Igor?
In the Deathstalker universe there exist psi-blockers, devices that espers using their powers in a given area. It is eventually revealed that Empress Lionstone had them created by extracting the brains from espers and sealing them in containers. The psychic screams of agony were what prevented espers using their abilities.
The later series replaced the original psi-blockers with genetically-cloned esper brains that could generate the same effects without the horror.
In Oblivion, third book of the Spaceforce series, the Chairman of the Fantasia Corporation turns out to have put his body in cryogenic suspension but kept his brain alive and active, so that he can still run his company via holographic avatar.
Ypsilon/Duktig in P.C. Jersilds En Levande Själ, who had the rest of his body amputated and his memory wiped.
Professor Dowell's Head by Alexamder Beliaev concerns a scientist who reanimated his dying genius colleague's head to request, trick, or beat (as needed) ideas out of him. Professor Dowell knows that his position is horrific, but is not as bitter as he himself would expect. He believes it's because he lost most of his endocrine system, so he can't get truly enraged.
Emperor Mollusk versus The Sinister Brain by A. Lee Martinez. The Brain turns out to be part of an Ancient Conspiracy of such brains called the Council of Egos who want to take over the universe. They consist of all the great minds of human history (except Hitler, who got flushed for being too argumentative). Albert Einstein also turned down the offer, claiming the process had turned them into delusional megalomaniacs. The Council think this idea is so ridiculous they spend a good deal of time laughing maniacally over it.
The Marquess of Watersford in The Curious Case of Spring-Heeled Jack ended up a brain in a jar, which was placed in the skull of an orangutan so that he can walk around. He gathers several morally ambiguous people this timeline's versions of Darwin, Galton, Florence Nightengale, Isambard Kingdom Brunel . . . . it's a weird book with the intent of capturing Jack's time-suit so that he can go back in time and prevent the accident that trapped him in this state.
The VUXG in Sector General are described as looking like prunes floating in bottles of liquid. To compensate for their lack of physical anatomy, they have ludicrously powerful telepathy and telekinesis.
The brainiacs in City of Devils are one of the many many kinds of monsters in the novel.
In Too Many Curses, one of the many captives left behind when the evil wizard Margle dies accidentally is what's left of his brother Yazpib, whom Margle defeated years before. Yazpib is slightly better off than usual for this trope, as his brain shares its jar with his eyes, teeth and tongue, which can still see and speak as they float freely in their preservative.
And Lady Cassandra, in The End of the World and New Earth, is a skin trampoline with two eyes and a mouth controlled by her enjarred brain. In New Earth she transfers herself to living bodies, but this destroys her original brain so she can't go back.
Wonder Woman: In the 1970s version, the episode "Gault's Brain" had one brain-in-jar villain with floating eyeballs and telekinesis.
This happens to Lister's "future self" (one of them, anyway) in Red Dwarf
Lister also mentioned in an early episode that his uncle's brain was in a jar and that it was really sad, as he wasn't dead yet.
"Mr. Newman" of the short-lived series Now and Again spent some time as a brain in a jar after getting hit by a train but before getting his new Super Soldier body.
Lexx. Slightly subverted in that the brains of the former His Divine Shadows somehow don't need jars in order to survive.
They may be sustained with protoblood. Though given how easily they're destroyed, maybe not - protoblood would make them invulnerable. Possibly a weaker derivative. Or maybe having housed the essence of His Divine Shadow makes them this tough as a side effect.
In Mystery Science Theater 3000, Brain Guy had his brain in a dish...that his body was carrying. He claimed that his species had evolved beyond the need for a body, despite the obvious helplessness of the exposed organ without a body to carry it around. Several skit gags involved separating his brain from its body or adulterating the brain dish with Mountain Dew or similar to get a funny reaction.
In the song "Lovecraft in Brooklyn" by The Mountain Goats, beings from beyond the stars are coming to put her our brains in mason jars.
"Lost in the New Real" by Arjen Lucassen ends with this, from the first track to near the end it appears the main character has been brought back to life through mad science, only for the Brain in a Jar reveal during the final track.
This set of emails between a 419 scammer and a wise guy.
The late Usenet personality Gharlane of Eddore always depicted himself as being a brain in a jar.
According to Marshall Brain, we'll likely all choose to be this way in a few decades.
Several Far Side cartoons played with this trope, including one where a Jan in the Pan-esque severed head begins screaming in horror at its circumstances, only to receive an anti-insanity slap from the mad scientist who created it. "Thanks, Professor, I needed that."
An ongoing story in Tom the Dancing Bug features the life of a disembodied brain in a vat. The brain's owner keeps it on his desk as a conversation piece, and uses his desktop computer to feed it simulated sense data that leads it to believe it is an ordinary human living out a humdrum existence in the real world.
SCP Foundation, SCP-2099 ("Brain in a Jar"). SCP-2099 is the brain of Jeremy Valdez, which floats in a glass jar filled with water, green food coloring, artificial flavoring, sugars and electrolytes. It uses devices (such as a robot and mechanical hands) to manipulate objects.
Bally's Xenon depict robots on the playfield with transparent skulls, with their organic-looking brains clearly visible inside.
Mind Flayers, aka the Illithid race has as the leaders Elder Brains. Gigantic Brains in Jars. With Psionic powers. These are created from the brains of a few illithids first to die in a colony and others are added to the pool later when possible, as a sort of immortality.
Various undead supplements have provided more normal-sized brains in jars, like here for example.
Ravenloft got a brain in a jar, salvaged alive from an accident victim by Dr. Frankenstein Expy, it's a mind-controlling criminal mastermind in Dementlieu.
Forgotten Realms has mind flayers of Oryndoll storing many brains of those they thought knew too much, alive and available for telepathic probing as a "library". Presumably their own divine Elder Brain could absorb all this, but then it would be pestered with unimportant questions.
The Pathfinder adventure module Wake Of The Watchers features a "brain archive" containing several of these.
Gamma World. Borgs, Permanent Cybernetic Installations and Think Tanks in 1st Edition. Borgs in 2nd Edition.
GURPS has a disadvantage called "No Physical Body" which turns you into this. You're immobile and anybody who interacts with you is likely to recoil in horror. So it kinda sucks, except that it gives you a ton of character points you can spend on magic/psionic powers or other mental abilities.
Second edition had it as a potential villain archetype. First edition, using the META-4 universe, had the Atomic Brain who was a former Manhattan Project researcher whose brain survived the explosion of an experiment. A combination of resentment at Oppenheimer taking credit for the atomic bomb and frustration over a lack of limbs led to the Atomic Brain becoming a supervillain.
A tiny bit of an aversion, however, in that the Atomic Brain's... brain... floated above his robotic body.
Full-conversion Cyborgs in Rifts are basically brains and a few vital organs wired into a robotic body.
Supplement Threats 2, section "Halberstam's Babies". The evil scientist Dr. Halberstam continues his experiments by extracting the brains of children and storing them in containers, then connecting them to the Matrix and training them to be super deckers.
Thomas Roxborough, a major shareholder in Aztecnology, is currently a mass of undifferentiated protoplasm (including his brain). Sort of a "cancer in a jar".
Aztechnology is rumored to be working on biocomputers - computers based on human brains floating in a vat of electrolytes.
Also how full cyborg conversion works.
Star Frontiers module SF1 Volturnus, Planet of Mystery. The slavebots in the Sathar Artifact are controlled by a Sathar's brain which is in a large fluid-filled flask. The flask is connected to a radio with wires.
In the Metroid video game series, Mother Brain, a re-occurring final boss, is just a brain in a tank, guarded by various gun turrets and organic barriers. It is supposedly a biological supercomputer.
In Super Metroid, once it is defeated, it rises up again attached to an insanely powerful T-rex-like robot body.
Metroid Prime 3: Corruption features the Aurora Units, which are also brain-like organic supercomputers in large tanks. There's even been some theories on how they may be related to Mother Brain in some way, fueled by the very large number of Mother Brain references made both in-game and in supplementary material but never fully elaborated upon as far as direct connections go.
... and eyes. The movie gets its chills from the eyes just staring at you.
The Bioenhancement Center facility, when constructed, gives you the page quote.
In Fallout 3, President Eden is practically an artificial Brain-in-a-box built by the Enclave to keep their superiority over others through these means, leading to a fascist regime.
In Fallout Tactics, Vault 0 is run by the Calculator combined with a series of if brains in jars, supposedly from the best and brightest, though as a joke the brains seem rather shallow—the politician, for example, is clearly modeled on Bill Clinton, and there's a porn star brain. In order to win the game you have to destroy all the brains and then confront the Calculator, who offers you the chance to join your own brain to it and thereby bring order to the chaos of the Calculator's damaged mind. General Barnaky, already a brain in a jar on top of a robot, also offers himself. Depending on what kind of game you played, or whether you take up one or other offer or refuse it and just let the counter run down, the game ending changes.
Not to mention Skynet from Fallout 2. Although he's technically an AI that wants to conquer the world, you bring him out into the world through a cybernetic brain inside a Brain Bot. You can also end up bringing a Chimp or normal human brain instead, but that isn't quite as good.
Or you can use an abnormal brain, which will render him The Load, too stupid to do anything but carry items (including comprehending that it's been fired). The only way to get this version of Skynet out of your party (thus making room for someone actually useful) is to kill it.
Also across all Fallout games is the Robobrain, a robot that has an organic brain as a CPU - notable in the fact that none of the brain's original thoughts are present (it is said that the brains used range from Chimpanzees to Humans).
In Fallout: New Vegas DLC Old World Blues, there's the Think Tanks, who are a group of Pre-War Mad Scientists who put their brains in floating robots with monitors for eyes and mouthes.
This also happens to the Player Character in this DLC as well. When you first arrive at the Think Tank your brain is extracted and replaced with cybernetic parts intended to allow your body to continue to function for simple slave labor. Somehow, as a result of a combination of an old head wound and a freak scientific accident, you retain coherent thought, even though your brain is elsewhere, allowing your "mind" to be in two places at once, with your brain being treated as a seperate entity. Yeah Old World Blues is weird.
There's also the K9000, a minigun powered by the brain of a dog. It'll even bark, whine and growl and includes cybernetic ears and noses.
Kingdom of Loathing allows you to fight the Brainsweeper, a Brain In A Jar that is powering a set of brooms. (For Science!) It Randomly Drops a Disembodied Brain in a jar, which you can use to Frankenstein together a chef, bartender, maid, or a few other things.
Doctor Brackman of Supreme Commander made himself into a brain in a jar to stay alive after his nominal death. One thousand years of constant warfare later, and he's still going strong as the leader and father of the Cybran Nation.
Psychonauts. Later in the game, the campers and teachers of a summer camp for psychics have their brains stolen by the Big Bad, who puts them into jars and uses them to make an army of deadly psychic tanks. Collecting all these 19 or so brains is a sidequest (each brain you find adds to your maximum HP).
In Command & Conquer: Red Alert 2, Yuri keeps several brains in jars to research psychic technology. In the Soviet campaign, he uses them to cheat death by uploading his mind into one of them. And in the expansion there is a very literal think tank...
The protagonist of Dead Head Fred is killed and reanimated in this form at the beginning of the game, though he is at least attached to his original body. His... predicament lets him switch his head with other things, each with their own gameplay uses.
F-Zero has Deathborn. It's the only part of his body still remaining after being reconstructed 3 times.That includes his Soul.
The Sims: Busting Out had a brain in a jar as furniture. In fact, said furniture is involved in one of the challenges.
Streets of Rage 3 has the recurring villain, Mr. X, show up as a brain in a tube. He still wishes to rule the city.
Mr. X: Quite easily, traitor. Let me show you! (Robo-Y flies into the room)
The BioDerm (artificially cloned/grown human pilot) "Mentor" in MissionForce: Cyberstorm is one of these, an experiment meant to test the feasibility of direct neural link to a HERC. It works - Mentor is scarily competent - but the tradeoff is a very short lifespan.
In Contra III: The Alien Wars, Red Falcon can be reduced to this. Of course, being a disembodied, floating brain only makes him deadlier, as he can then use a variety of psychic weapons and (in Hard mode) a metallic, armored sheath with octopus-like tentacles.
Shin Megami Tensei's interpretation of Omoikane, Shinto goddess of wisdom and intelligence, depicts "her" as a disembodied brain with eyes and several dozen feelers.
A brain in a jar is the whole point of the game Cortex Command. Sometimes, it's hanging in a bunker, and sometimes it's on a robotic exoskeleton and can move, though it's fragile and if it dies, you fail.
Joe Musashi from the Shinobi games had to deal with B.I.A.Js quite a few times in his missions. In Revenge of Shinobi a stage taking place aboard a huge military transport ended with a Boss Battle against a Brain in a Jar that actually controlled the transport. In Shinobi 3 one of the missions takes place in a biowarfare lab where he would deal with Brains that broke out of their jars, Brains with Wings, and at the end, a Brain in a Dalek-esque battle machine.
In episode one of Sam & Max: Freelance Police: The Devil's Playhouse, "The Penal Zone", Sam and Max encounter a disembodied alien brain named Gordon on General Skun-ka'pe's ship. As suggested by the title of episode three, "They Stole Max's Brain!", Max ends up spending some time as one of these.
Life Line/Operator's Side: Rio's father, whom she had thought dead, has become this. His brain was recovered and was being used to further research into the Philosopher's Stone. Major, major Tear Jerker moment when she finds out and he asks to be shut down.
Tampo, the first boss of Stinkoman 20X6, is first seen as a mechanized Brain in a Jar that was destroyed by Stinkoman prior to the game's first level. The level ends with Tampo's brain coming back to get Stinkoman for revenge.
One of the bosses of Metal Slug 6 is a humongous brain with eyeballs in a jar... on top of an equally huge alien mecha. It's one of the hardest boss fights in the game.
Moreover, that anyone injured badly enough would end up with their head in a jar and with a few punchlines at their expense (usually by Ennesby, embittered over not having a body in the first place) was a running theme, especially earlier in the comic's run. Full-body regeneration has also been used since as a plot device, as once you get started there's really no need to regenerate a body EXACTLY like your old one. If your vanity or your job demands require a physical upgrade, well, here's your chance! More muscle (Nick), more height (Elf), less fat (Thurl and Xinchub), you can have a whole new you from the shoulders down. (why don't people do it all the time, then? It's expensive!)
Supertron: Supertron (actually named Simon)'s father is basically a brain in a jar, which also houses his eyes, intestines, and other organs.
At one point he builds a supercomputer out of a bunch of cloned Hitler jar-brains wired together.
A Brain in a Jar alien makes an appearance in thisSluggy Freelance strip, with the added twist that the creature's brain is divided into a right and left side, each in separate jars.
Alien: You just ate the left side of our brain, the one that handles all logic. I'm the abstract right side! I think I'll go paint my emotions now! Oooh! Something shiny!
In Homestuck, Dave comes across the alchemy combination that makes Dave's Brain In A Jar during his experiments with Item Crafting. It's too expensive for him to make because the organ is virtually inimitable, but he uses the code in alchemy to make the SBAHJifier camera.
The super-villain Dr. Haynus from Greystone Inn and its sequel comic Evil Inc. is a disembodied brain in a jar. As he is on top of a living puppy with a mind of his own, Haynus unfortunately feels the humiliation of not having control over its actions: Anyone can get rid of Haynus by simply using a ball or cookies.
Hector Con Carne's Brain in Evil Con Carne. Variation in that his stomach also is in a jar... and developed its own sentience. And both are occupying the body of a Russian circus bear named Boskov who can still act on his own despite his brain being replaced with Hector's. It's a weird show.
Futurama had the heads of various 19th-21st century personalities preserved in jars, including Richard Nixon, who eventually became president again. Used more for comedy and satire than creepiness. It was never explained exactly how, say, George Washington's head could have been preserved in the first place. Also, the main antagonists of several episodes are flying brains outside of their jars.
Done to an extent in "How Hermes Requisitioned His Groove Back", where Bender's personality and intelligence are downloaded into a floppy disk.
Inverted with Earth President Nixon's vice president, Spiro T. Agnew, who is a headless body.
They eventually Hand Waved the process as being a form of limited time travel; by incorporating some kind of powdered opal into the fluid heads are kept in, they create a tiny bubble in which the heads are perpetually in the time period during which they were alive. Presumably a certain amount of cloning is involved for certain heads as well.
The "powdered opal" explanation actually creates a problem, because it contradicts something from earlier in the series. In the episode "A Leela of Her Own," Leela visits the Blernsball Hall of Fame and meets Hank Aaron XXIV, a descendant of the original Hank Aaron. The original Hank Aaron's head in a jar is also present at the Hall of Fame as an exhibit, and Hank Aaron XXIV drinks from his head jar without getting sent back to his era.
After starting out as a human, Baxter Stockman eventually becomes one of these in the second Teenage Mutant Ninja Turtles series. The Shredder, of all villains, quips that "You should have quit while you were a head." Also, in the Fast Forward episode "The Journal", the turtles read about future events in their lives, including Donatello being reduced to a brain in a jar... with a mask on. The journal is then revealed to be a hoax.
The Fairly OddParents: In "Future Lost", the evil brain that aspired to take over had a strange weakness - put juice pills in its tank, and it would get a Brain Freeze.
Not just that. They also dumped some ice into it, making a giant slushie.
Also, every Yugopotamian has their brain clearly visable in a glass dome on their heads.
In Buzz Lightyear of Star Command, while the Star Command employs the Little Green Men seen in Toy Story, Zurg's minions are brains in jars (who frequently mention this situation when the boss complains).
Tactical Commander Owen Negata from Adventures of the Galaxy Rangers. A BETA research scientist and tactician, he was killed in the Supertrooper Riot (though we don't learn this until later). What was left of him can fit into a little jar attached to a 1.5 meter by one meter repulsorlift platform. Zozo is rather shocked by it.
Zozo:That's Commander Negata?!
Waldo: His brain unit. His body died years ago.
An episode of Jimmy Two-Shoes had Jimmy and Beezy accidently knocking the brain out of their favorite soccer player's head. By the end of the episode, Beezy still hasn't given it back, keeping it in a jar among his memorabelia.
Animats or Cultured Neuronal Networks are almost a Real Life version of this trope, almost being that they aren't complete brains (and usually animal neurons).
According to Pat R's series of articles on the Final Fantasy series, when an intern suggested the Job System during the development of Final Fantasy III, Hironobu Sakaguchi (the creator of the series) responded by pausing blankly, heaping rewards on him, then chloroforming him and putting his brain in a jar so that Squaresoft would never be without his genius. The article goes on to describe some of the brain's other accomplishments, before its tragic downfall at the hands of the designer of Final Fantasy II.
Averted by Mary Roach, author of Stiff, a nonfiction book about cadavers. Investigating the possible fates which await deceased human bodies, Roach considered donating her own to Harvard's medical school, in hopes of becoming a brain in a jar. To her disappointment, she learned that human brains preserved there for medical and scientific research are kept in plastic food containers, which hardly seemed worth it.
Dr. Albert Einstein requested in his will that his brain be removed for study and the rest of his body cremated. The brain is currently spread across multiple jars and a few dozen microscope slide.
According to the Boltzmann brain hypothesis, if one considers the probability of our current situation as self-aware entities embedded in an organized environment, versus the probability of stand-alone self-aware entities existing in a featureless thermodynamic "soup", then the latter should be vastly more probable than the former if both scenarios are to be created out of random fluctuation.
Number six on Cracked's The 8 Creepiest Places on Earth (Part 4), an abandoned underground Soviet beneath Moscow filled with brains in jars, which has virtually no information about it nor indication as to why it was abandoned in the first place.
A functioning brain in a jar would be surprisingly difficult to accomplish in real life, at least without major personality changes - to the point of possibly no longer having a recognisably human outlook - since any number of hormonal and even metabolic functions performed in other parts of the body contribute significantly to brain function.