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Brain Monster

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Andross: Only I have the brains to rule Lylat!
Fox McCloud: So, Andross, you show your true form.

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. If these brain monsters have other body parts, like eyes, a mouth and/or appendages, they will be attached directly to their brain.
  • Acranial Monster: A monster that has an incomplete skull, thus exposing their brain.

A sister-trope of Brain in a Jar, although a 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. Compare with Oculothorax, where the monster is a giant eye.


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    Anime and Manga 
  • Void, the 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.
  • In JoJo's Bizarre Adventure: Battle Tendency, the Pillar Man Esidisi's superhuman physiology allowed him to survive as just a disembodied brain and nerves after the rest of his body was destroyed by Joseph's Hamon.
  • 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.
  • Tak from Space Family Carlvinson is a brain with a spinal column, plus arms and legs to move around and interact with stuff. For a brain creature, he's also pretty ditzy and goofy, though by no means the dumbest in the cast.

    Comic Books 
  • B.P.R.D.: The 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.
  • The DCU:
    • Several incarnations of the Brain from Doom Patrol — 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 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.
    • The Earthwar Saga: The leader of the Resource Raiders, one of the enemies of the Legion of Super-Heroes, is a huge floating brain with a pair of bulging eyes and four prehensile tentacles.
    • Some incarnations of the Superman villain Brainiac have an exposed brain beneath his skull-diodes. The heroic Brainiac 417 of DC One Million is a disembodied brain encased in a humanoid force-field.
  • Marvel Universe:
    • 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.
    • One arc of Thunderbolts has 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.

    Comic Strips 

    Film — Animation 
  • The principal antagonist of Gandahar 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 
  • The Brain (1988) features an alien that resembles a gigantic brain with a face as the titular monster.
  • 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.
  • Fiend Without a Face features Invisible Monsters that, when revealed, are actually slimy crawling human brains. Said brains strangle victims with their spinal cords.
  • In Guardians of the Galaxy Vol. 2, Ego's truest form, 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 Supreme Martian Intelligence in Invaders from Mars (1986) looks like a brain with two vestigial limbs and a face (his eyes also have two pupils each), attached to an appendage that comes out of a sphincter-like opening in its organic-looking underground spaceship.
  • The invading Martians from 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 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 Grand Lunar from 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 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 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.
  • In Rudy Rucker's Master of Space and Time, a giant brain becomes the messiah of a Religion of Evil in an alternate dimension, spawning 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.
  • In The War of the Worlds (1898), 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.
  • A Wrinkle in Time: The Big Bad IT is a huge, disembodied brain with mind-control abilities that involve making the victim think in repetitive patterns.

    Live-Action TV 

    Puppet Shows 
  • Fern, the female monster in The Jim Henson Hour "Hurting Something" skits, had an exposed brain with tendrils of skin holding it in place.
  • Craniac in the Muppets Tonight "Pigs In Space: Deep Dish Nine" skits has a head that looks like a brain with eyes and a mouth.

    Tabletop Games 
  • Dungeons & Dragons: This is a general theme of illithid-aligned creatures (although illithids merely exhibit My Brain Is Big, perhaps because their octopoid heads are stretchy enough to contain them).
    • Their rulers, Elder brains, are literal giant brains floating 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 us, if you survive an encounter, you'll never want to go without Protection from Evil and Good again. Where intellect devourers come from depends on the edition. Some sources say that illithids create them by transforming a humanoid's brain, but according to other the intellect devourer is an alien species that starts life as a smaller, less intelligent brain creature that also has tentacles called an ustilagor which loses the tentacles when they become an adult.
    • Grells resemble giant floating brains, except with squid-like beaks and ten tentacles that inject paralyzing venom into their prey. They are technically not a true brain monster, as their bodies only happen to look like brains.
    • Cranium Rats are super-intelligent rats whose oversized brains are exposed. They have telepathic abilities that allow them to become smarter when large groups of them are close together.
    • A Brain in a Jar is classified as a type of undead and they have psychic powers.
  • 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 that 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.
  • Warhammer 40,000: Several Tyranid creatures, especially those with strong psychic powers, have partially exposed brains.
  • Eclipse Phase: One of the usual adversaries are the Exhumans, a rather diverse group of radical body modificationists, evilutionary biologists, and wannabe evil overlords, having very little in common besides all agreeing that (trans-) humanity has run its course and will be replaced by them. "Brain on spider legs diabolical mastermind with a God complex" is common enough to be an in-universe category in itself.

    Video Games 
  • Alien Syndrome's level 1 boss is a big brain with a bonus supplemental brain attached.
  • Ashes 2063: Haunts, hostile ghost-like entities, are actually a somehow-living brain and spine disguised behind a projection of a corpse, as can be seen when you kill one. Presumably, they're a type of mutant like the Cannibals.
  • The final boss of Beast Busters looks like a human scientist, but it's only the disguise of a floating one-eyed alien brain creature that phases through the wall. After you defeat it, however, the battle is not yet over — its remains crawl into a massive contraption, powering it for the real final battle.
  • The Binding of Isaac:
  • Blasphemous has Our Lady of the Charred Visage, whose pulsating brain is also her weak point.
  • In Blaster Master and its remake, Blaster Master Zero, the boss of the Forest Area is a floating brain monster called Mother Brain. In the original, it's a standard Warm-Up Boss with indestructible orbiting brain satellites. It loses those in Zero in exchange for gaining some plant monster traits.
  • Bloodborne has Amygdala and its brethren, whose head consists of a mostly exposed brain occasionally covered in eyes. In addition, the Brain of Mensis is a giant brain covered in eyes.
  • 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.
  • Chaos Heat have a massive brain monster as a boss in the lab, as large as the pool it's spawned from with neural veins sticking out the pool's edges and it's sole facial features being a single protruding eye. It's a difficult Sequential Boss that needs to be killed thrice to boot.
  • 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 pathfinding, greatly complicating avoiding being overrun by them.
  • The final form of Neibiros, the Final Boss of Dragon Blaze 2000 (it's a Sequential Boss, you'll need to defeat his draconic, behemoth and monster form first) is a massive brain-like form with Neibiros' head growing out from its side. Said giant brain also has horns, a giant central eye, and the ability to spam fireballs all over the screen. Upon defeat, it turns into a smaller, winged brain and continues fighting before finally going down for good.
  • Doom:
    • Doom: The final boss of the third and fourth episodes — the Spider Mastermind — is essentially a giant brain carried by a robot body.
    • Doom II:
      • The Spider Mastermind's children are the Arachnotrons, which are smaller versions with automatic plasma guns.
      • The 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.
    • Doom³: It's not immediately noticeable, but the Cacodemon design has an exposed brain on top of its head.
  • 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.
  • 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.
  • GunBuster inexplicably have a human-sized brain in a cylindrical tube as the mastermind of the cyborg villains and the game's last boss. The brain even taunts you verbally as you approach it.
  • Iron Meat has a boss being a tank coated with Meat from the mutant spread, where besides having flesh-like organs growing on it's sides, also have a gigantic, exposed brain growing out of the cockpit, which controls it into attacking the players.
  • Isolated Warrior have a giant, throbbing, floating brain as the third boss, who managed to construct a gigantic mechanical head for itself. It automatically encasing a shell around it as soon as you enter, and you'll need to bypass it's defenses to shoot the brain until it blows up.
  • These are featured in the first, third and fifth Gradius games. 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.
  • Metal Slug:
    • In 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.
    • Metal Slug 6 has the Brain Robot, a giant mecha Brain in a Jar and an Advancing Boss of Doom, that pursue the players relentlessly in the Beijing sewer system.
  • 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 a Wetware CPU 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, mechanized body.
  • Monster Maulers has Brain Golem from Salamander appear, now equipped with Eye Beams.
  • Dr. Brain's penultimate form in Not Dying Today. At the first phase of the boss fight, he assumes a humanoid form, save for his gigantic pulsating brain under a glass dome, but once you defeat him the brain then supersizes and consumes him, turning into a gigantic floating brain controlling a hovering platform to attack.
  • Shade: Wrath of Angels contains floating, deformed brains in the Otherworld, who can blast you from afar with mental energy bolts.


    Web Original 
  • Lampshaded in Dragon Ball Z Abridged's version of Dragon Ball Z: The World's Strongest. Dr. Wheelo is unaware and has to be told that his brain has absorbed a lot of the embalming fluid it's suspended in, which caused it to grow, much to his dismay.
    "Why is it the size of a greyhound?"
    "THE BUS?!"
  • A few stranger strains from Goodbye Strangers, such as the Condroni, have bodies that appear to be completely filled with human brain tissue when cut open. This does not make them smart however, as like most strangers, their insides don't appear to have any function besides being creepy.
  • Neopets
    • The Brain Tree, which gives out quests in the form of 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.
    • Mutant pets were subjected to a Painful Transformation by the site's Big Bad. As their name implies, their main trait is Body Horror of all sorts, and two of them have their brain exposed, in different ways. Mutant Kacheeks have theirs so swollen that it melds through the top of their heads. Mutant Draiks have it showing through a visible skull fracture.
  • Mortasheen has many, many monsters based on brains, or just brain-like in appearance. They are often — but not always — associated with Psychic Powers of some kind.
    • Encephalobe is the result of a zombie's brain becoming an independent monster of its own — although they start trapped in their parent body.
    • Drainwave is a brain/balloon hybrid that feeds on other beings' minds.
    • Abcoulix is best described as a toad with a brain for a body, but the brain is for electricity generation rather than for intelligence.
    • Corpusite is not normally this trope, but its brain can "escape" and take residence into another body (at least some Mortasheen citizens consider this a mutually beneficial relationship rather than pure body theft).
    • Scumbat looks like this trope (at least in the mature phase), but it is actually a parasitic fungus with a brain-shaped "fruit".
    • Necromon is a monster that evolved from a homunculoid, the Mortasheen equivalent of Nanomachines. For some reason, it looks like a brain perched atop a tiny body.
    • Several "garbage" monsters (leftovers from monster creation, useless and generally pitiful) are made of brain tissue. These include the unintelligent huhhk and ekeblange, as well as the massive bleevus which has a powerful mind but whose thoughts are entirely incoherent.

    Western Animation 
  • 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 (1998) has his enlarged brain protected by (and visible under) 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.
  • Tigtone: The villainous Brainbow, who is a former human whose brain and nervous system were magically separated and act independently. He has an enmity with his other half, a rainbow colored skeleton named Rainbone.

    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):


Intellect Devourer

An intellect devourer resembles a walking brain protected by a crusty covering and set on bestial clawed legs. This foul aberration feeds on the intelligence of sentient creatures, taking over a victim's body on behalf of its mind flayer masters.

How well does it match the trope?

5 (3 votes)

Example of:

Main / BrainMonster

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