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Brain Monster

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The brain. A big, juicy, wrinkled organ on our head that is protected by the skull for a good reason. Now, imagine when it's not...

There are two types of monstrous brains:

  • Just Brain: The brain moves around by itself. It might have some bits attached, such as legs, hovering jets or helicopter rudders, but its main "body" is a brain. Alternatively, it is stationary, and attached to something.
  • Acranial Monster: A monster that has an incomplete skull, thus exposing their brain.

A sister-trope of Brain in a Jar, although of lot of these brains don't really need the jar life-support system, as well as the furthest extension of My Brain Is Big.

Subtrope of Evil Is Visceral and Body Horror, and thusly, is always played for Nausea Fuel.



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    Anime and Manga 
  • Void, oldest member and nominal leader of the God Hand in Berserk, is a looming figure in a high-collared cape topped by ghastly head which is mostly bulging, exposed brain.
  • Vademon from Digimon Adventure has a huge exposed brain, seeing that he's an alien Digimon.
  • Big Bad Dr. Wheelo of Dragon Ball Z: The World's Strongest had his brain preserved in a jar by his assistant before he died, and is currently searching for the world's strongest warrior to serve as a host body. For some reason, the process also made his brain gigantic; how he expects to transplant it into a human-sized skull is unknown.
    • Lampshaded in Team Four Star's abridged version of the movie. Wheelo is unaware, and has to be told his brain has absorbed a lot of the embalming fluid it's suspended in, which caused it to grow. To his dismay.
      "Why is it the size of a greyhound?"
      "THE BUS?!"
  • The Nomus of My Hero Academia are former humans who have been bioengineered by the Big Bad so that their bodies can support multiple Quirks. They all look almost completely different, but the one feature that ties them all together is their exposed brains. Characters who are unfamiliar with the term "Nomu"note  refer to them as "brain guy" or some variation thereof.

    Comic Books 
  • Several incarnations of Brain of The DCU — as the disembodied, preserved, sentient Brain in a Jar of a Mad Scientist. Together with his sentient gorilla servant/boyfriend Mallah, the two of them would go on to gather the Brotherhood of Evil.
  • The B.P.R.D. short comic that introduced Lobster Johnson involves a scientist who gained Psychic Powers in an experiment, then used those powers to kill his colleagues. When the Lobster shoots the psychic in the head, his brain crawls out of the bullet hole, grows several times larger, then flies around the room. The Lobster barely kills the mutant brain before it strangles him with its spinal cord.
  • Amadeus Cho's subplot in The Incredible Hercules pits him against Boltzmann Brains; disembodied brains that are hypercomputer quantum constructs capable of creating virtual scenarios in pocket dimensions at will. They also shoot bolts of electricity.
  • An arc of Thunderbolts had the titular team stuck in hell due to the machinations of Blackheart. There they encounter a Magic Mirror that conjures the antithesis of whoever is reflected in it to fight them. The Red Hulk gets Encephalon, pretty much a Hulk in stature but made entirely out of brain.
  • The Gil'Dishpan or Gil'Dan, who have fought Superboy and the Legion of Super-Heroes and were part of the Alien Alliance in Invasion!, look like misshapen brain-tubeworm things in tentacle covered bubbles.

    Comic Strips 

    Film — Animation 
  • The principal antagonist of the French film Gandahar, a.k.a Light Years, is a giant brain, made by the people of the utopian city of Gandahar as a prototype organic computer. When the superbrain didn't work out as planned, it was dumped in the ocean and forgotten. Interestingly, when the heroes first encounter this giant brain, it seems docile, and even gives the heroes the tool for its own destruction.
  • In The Iron Giant Hogarth stays up past his bedtime watching TV, and the movie playing seems to be a Science Fiction B-Movie about killer brains. Just before the TV loses reception it shows the scientist character being attacked by a brain with tentacles. This is probably an Affectionate Parody of Fiend Without a Face.

    Film — Live-Action 
  • Gor and Vol from The Brain from Planet Arous are aliens that resemble giant disembodied floating brains. The former wants to take over the universe, the latter wants to stop him.
  • The 1958 film Fiend Without a Face featured invisible monsters that when revealed are actually slimy crawling human brains. Said brains strangle victims with their spinal cords.
  • The Brain (1988) (not to be confused with the 1969 comedy of the same name) featured an alien that resembled a gigantic brain with a face as the titular monster.
  • In The Time Machine (2002), the Morlock leader is of a caste in which the brain has become so enlarged that it's not only visibly exposed on the back of his head, but its lobes extend halfway down his back as well.
  • The invading Martians from Tim Burton's Mars Attacks! are the acranial type. Their brains visibly pulsate and explode inside their clear helmets when exposed to their Weaksauce Weakness: really bad singing.
  • In Guardians of the Galaxy Vol. 2, the truest form of Ego The Living Planet, which also seems to function as his core, is a gigantic, brain that glows with energy. Interestingly enough, this incarnation of him seems to be a literal Boltzmann brain.

  • The Grand Lunar from H. G. Wells' work The First Men in the Moon is the ruler of the "Moonies", and rests in the throne room with his exposed brain taking up most of the cathedral-like ceiling space. There are lesser Moonies that hover around moistening this huge brain. The Grand Lunar is Lawful Neutral, but takes Doctor Cavor prisoner on the belief that humans are intelligent anarchists.
  • In another HG Wells story, The War of the Worlds, the Martians, to the human eye, appear as huge brains with tentacles, having pared their bodies down to just the vital organs (brain, heart, lungs, and hands, "the agent and educator of the brain"). Their Tripod Terror giant robots are "bodies" built for the needs of the moment, and they "eat" by draining the nutrient-rich blood of lesser animals, including people.
  • In Harry Potter and the Order of the Phoenix Ron gets attacked by tentacled brains in the Department of Mysteries that Mind Rape and leave gouges behind when they touch someone.
  • In the Lensman series novel Galactic Patrol, Mentor of Arisia is revealed to Kimball Kinnison to be (barring a few minor bits and appendages) "simply and solely a brain." Then in Second Stage Lensmen the Boskonian Prime Minister Fossten is revealed to be a nearly identical brain, explained by his being a renegade Arisian. Except that this was a false appearance in both cases, arranged by Mentor to hide from Kinnison that Fossten was really Gharlane of Eddore.
  • In Rudy Rucker's Master of Space and Time, a giant brain became the Messiah of a Religion of Evil in an alternate dimension. Then it spawned regular-sized brains that can move around by crawling, attach to people's backs and mind-control them.
  • Possible Tomorrows: The 1973 Coronet cover seems to be a brain (with human-like eyes open in fear) as part of a radio tower. No, it doesn't show up in any of the stories.
  • Star Wars Legends: The Yuuzhan Vong use a semi-telepathic creature called a yammosk to coordinate their forces. (Yammosk actually communicates through gravity pulses.) A massive yammosk, the World Brain, is introduced to manage the Vong-forming of Coruscant.
  • Madeleine L'Engle's novel A Wrinkle in Time. The Big Bad IT is a huge disembodied brain. It has Mind Control abilities that involve making the victim think in repetitive patterns.
  • In Edmond Hamilton's The Man who Evolved, the protagonist evolves (after several intermediate passages) into a giant brain with tentacles, and then into a giant brain with Psychic Powers that no longer even needs tentacles.

    Live-Action TV 

    Tabletop Games 
  • Dungeons & Dragons
    • Illithid elder brains, which float in large brine pools in illithid cities. They are made up of the combined brains of old illithids that sacrificed themselves to join it.
    • The Intellect Devourer is basically a brain running around on four little legs. Its modus operandi is to crack a victim's skull open, remove the brain and then squeeze inside, taking over the body. Believe me, if you survive an encounter, you'll never want to go without Protection from Evil and Good again.
    • Grells resemble giant floating brains, except with squid-like beaks and ten tentacles that inject paralyzing venom into their prey.
  • In Warhammer 40,000, several Tyranid creatures, especially those with strong psychic powers, have partially exposed brains.
  • Genius: The Transgression also throws in its own version of Boltzmann Brains; this time, as super-intelligent and super-insane giant floating brains that, due to how Boltzmann Brains come into being, remember things that never happened, including massive crimes the targets of their aggression never committed. And being geniuses of their own, and quite insane at that, they tend to superimpose their own version of events over nearby reality. Notably, the thought experiment about them existing was what actually caused them to exist; disproven theories always leave a Mania-infused trace.

    Video Games 
  • Metroid
    • In Metroid the final boss, Mother Brain, is a massive brain in a tank, with a laser shooting eye. It's stated that she started off as an organic computer built by the Chozo, who took command of the Space Pirates.
    • In Super Metroid, Mother Brain reappears as the final boss this time as an "acranial" example, having gained a massive mechanised body.
  • Featured in Gradius, Gradius 3 and Gradius 5. Many final bosses of the series are usually giant, brain-like beings. As a Running Gag through the series, they are often ridiculously easy to defeat.
  • The first boss of Stinkoman 20X6 is the brain of the Humongous Mecha Stinkoman defeated in the opening cutscene.
  • Doom series
    • The first final boss - the Spider Mastermind - was essentially a giant brain carried by a robot body. Its children in Doom II are the Arachnotrons, which are basically smaller versions with plasma guns.
    • Doom 2's final boss is the Icon of Sin, a giant skeletal goat face with an exposed brain as a weak point. It is only vulnerable to rockets fired into it from a certain angle, however.
  • One of Duke Nukem 3D's monsters is Octobrain, a large floating brain-like creature with tentacles hanging down beneath, 3 red eyes and a large mandibled mouth.
  • The first XCOM game also features the Alien Brain on Mars as the Big Bad.
  • The demon Omoikane from Shin Megami Tensei series isn't evil, but is a floating brain with tentacles nevertheless.
  • Metal Slug 3: Rootmars, the Final Boss, is an alien with a big exposed brain that serves as his weak point. Said brain can occasionally emit a shockwave that is hard to dodge.
  • The final boss of Vectorman 2 is a giant black widow spider with an exposed brain in her thorax. Sure enough, that exposed brain is her weak point.
  • The Lickers of Resident Evil are T-Virus zombies which have mutated further and have had their brain extend out of their cranium. Despite the (relative) boost in intelligence, they also become more bestial; crawling on all fours and attacking based on sound with an elongated tongue.
  • The Binding of Isaac has enemies that are large brains (simply called Brains) that crawl around the floor, leaving a trail of blood that damages you if you step on it. There's also an even larger variant, called a Membrain, that splits into two regular Brains when it dies. Afterbirth Plus introduced a green variant called "Toxic Mind" that moves diagonally rather than horizontally and vertically.
  • The Mind Cripplers in Underworld Ascendant are floating humanoid brains that aggressively attack the unwary with psychic powers.
  • Deadly Rooms of Death has the brain enemy. It just sits there and doesn't attack. The problem is that it gives all other enemies much improved path finding, greatly complicating avoiding being overrun by them.
  • The Weirdboy in Dawn of War 2 has an upgrade called Bigger Brains, the icon for which shows his brain swelling out of his skull.
  • The fourth guardian in Unepic, the aptly-named Neuron, is a giant floating brain with a single eye which lives in the castle's library. It has an ungodly amount of Psychic Powers — up to an including mind-controlling your character or causing an Interface Screw — that make it one of the trickiest (and most annoying) enemies in the game.
  • Bloodborne has Amygdala and its brethren, whose head consists of a mostly-exposed brain occasionally covered in eyes. As well, the Brain of Mensis is a giant brain covered in eyes.
  • In Terraria, the boss of the Crimson is the Brain of Cthulhu, a giant demon brain with some tentacles and a few vertebrae sticking out of the bottom. Once you kill the Creepers surrounding it, the two hemispheres open up, revealing a beating heart with an eye on it.
  • EarthBound Beginnings has the Cerebrum, which looks like a Brain in a Jar on two legs. It can cast just about any high-level PSI ability, which with its high speed and HP makes it a formidable late-game enemy, but a successful PSI Block will render it all but harmless and a ripe target for Mana Drain.


    Web Original 
  • Neopets has the Brain Tree, which gives out quests in the form of a questions you must answer. The rationale behind this behavior is that the Brain Tree loves knowledge but, being rooted to the spot, it must rely on others to find information.

    Western Animation 
  • The Brains from The Adventures of Jimmy Neutron: Boy Genius, contestants in the Galactic Showdown game. They bragged on how they evolved to not need bodies anymore, as they consisted of nothing but floating brains.
  • Gunter briefly becomes this leading up to the sixth season finale of Adventure Time, after a head injury literally splits his head open, and Gunter remembers that he is in fact Orgalorg, an ancient Eldritch Abomination from space, prompting his brain to hijack Princess Bubblegum's spaceship.
  • Ben's Alien Brainsorm from Ben 10: Alien Force can open his head to reveal his oversized brain and shoot electricity from it.
  • In Big Guy and Rusty the Boy Robot Dr. Neugog transforms into a giant spider monster with an exposed brain, that drains other people's intelligence to make himself smarter.
  • The Darkwing Duck episode "Heavy Mental" revolves around a machine that gives the user Psychic Powers and enlarges their brain as a side effect. At the episode's climax, the villain crank the machine Up to Eleven and turns himself into a truck-sized, floating brain. Darkwing and his friends beat him by making him think too much during the power-up process, which blows him up, making this one of the Squickiest episodes of the series.
  • What other show has such a creature as its main character other than Evil Con Carne?
  • The Lobe, the Mad Scientist and Arch-Enemy of Freakazoid!.
  • The Brain Spawn of Futurama are a race of giant, flying, telekinetic brains with the ability to telepathically drain the intelligence of animals, robots, and some plants. Their goal is to store all knowledge in the universe in a giant database, then destroy the universe so that no new knowledge will be generated, because apparently that's less work than making continual updates for all eternity.
  • An episode of George Shrinks featured these in a B-Movie.
  • Mojo Jojo from The Powerpuff Girls has his enlarged brain protected by a helmet.
  • Krang, as seen in Teenage Mutant Ninja Turtles (1987), has been reduced to a brain thanks to a judgment in his home dimension of Dimension X. He went through several iterations of armor to protect this squishy body until he reached a full robotic suit of armor.

    Real Life 
  • The Barreleyes are a family of deep-sea fish that have evolved transparent heads so that their large, tube-shaped eyes can look straight up through their skulls to see potential prey imposed upon the light filtering down through the water above. This has the side effect of making it look like their brains are exposed.


Video Example(s):


Psychic Death Tanks

The Psychic Death Tanks are tanks powered by the brains of psychic children.

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