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‘Defective product’.... Me...?!! A defective product... You dare claim that I am defective...!!

—Mother Brain[2]

Mother Brain (マザーブレイン Mazā Burein?), sometimes shortened to simply Mother[3], is a recurring antagonist in the Metroid series. She is an ambitious and ill-tempered artificial intelligence created by the Chozo, who turned against them to lead the Space Pirates instead. As the head of the Pirates on Zebes, Mother Brain improved their military strength and thus, along with her plan to weaponize the Metroids, posed a massive threat to galactic society.

Mother Brain served as the main antagonist in Metroid, Super Metroid, and Metroid: Zero Mission. She is seen in a flashback during Metroid: Other M, and an android based on her was the antagonist of that game as well. On the Japanese website for Zero Mission, she is given the title Mad Overseer (狂気の支配者?).



Mother Brain's drone observes a frightened Samus.

Mother Brain's backstory is exclusively explored in the Metroid manga, revealing she was a computer interface created by the Chozo to oversee their colony on Zebes. She was present when Old Bird brought the orphaned Samus Aran to Zebes; Mother Brain inspected the child with a drone and disregarded her as a weak creature who wouldn't survive the planet's harsh environment. At the Chozo's behest, she assisted in the Body Adaptation process for Samus, and would also go on to help create her Power Suit, keeping this fact a secret for years.


The Chozo consult Mother Brain on Metroid development.

Mother Brain held a tenuous relationship with Samus as she grew into an adolescent, condescendingly overseeing Samus' training exercises alongside Old Bird and Gray Voice. During this time, Mother Brain kept her creators up to date with reports in the propagation of Metroids on SR388. Mother Brain and Gray Voice also cooperated to use Work Robots to exterminate the Badger Clover and Iono Feria, much to the ire of Samus.

Years after Samus left Zebes, Mother Brain betrayed the Chozo to help the Space Pirates invade and conquer the planet. Demonstrating her superiority complex, she voiced her frustrations with her creators and claimed she had long surpassed them. She calculated that taking control of the Pirates would allow her to bring order to the universe through force, giving the role of Space Pirate commander to both Ridley and Gray Voice, the only sympathetic Chozo. When Samus was captured, Mother Brain tried to persuade her to become a commander, revealing she had created her treasured Power Suit and claiming that the Chozo's true intention for Samus was to use her as a bioweapon. However, Samus vehemently refused.

Soon after, Mother Brain was attacked by Gray Voice when he revealed he was only cooperating to win her trust. He called her a "defective" product and speculated that she developed fear, hatred, and jealousy of other sentient life, in particular of Samus due to the orphan showing more promise at protecting the cosmos than Mother Brain. These statements left Mother Brain shaken, pleading for Ridley's help when he arrived to defend her. As Ridley mortally wounded Gray Voice, Mother Brain was quick to mock her attacker and called him "just a bird who can't even fly". Samus escaped Mother Brain's clutches with the Chozo refugees, leaving Mother Brain in control of Zebes, from where Mother Brain would use the Space Pirates to terrorize the galaxy.

Eventually, Mother Brain's Space Pirate forces ambushed a Galactic Federation shuttle that had obtained a Metroid larva from SR388. They returned with it to Zebes, allowing Mother Brain to begin her plan to use Metroids as bioweapons. She began cloning them via exposure to Beta-Rays, planning to telepathically organize them into attack forces.[4]



Mother Brain is the final boss of the original Metroid, awaiting Samus in the depths of Tourian on Zebes. Her Command Center forces Samus to maneuver defense systems and hazards, including 15 Cannons, 14 Rinka generators, two pools of lava, and five Zebetite barriers. There is neither health nor ammunition to be found in the room, therefore a miscalculated move can result in Samus being overwhelmed by Mother Brain's defenses and build up immense damage unless she leaves the room entirely.

The Zebetites are the first targets to destroy before reaching Mother Brain and Samus can use the nearby floating platforms to help line up her Missile shots against them. However, these platforms are a double-edge sword as they are positioned in the line of fire of the Cannons above. Samus can alternatively exploit the infinitely spawning Rinkas with her Ice beam by turning them into makeshift platforms in safer spots. As she approaches the end of the corridor, the floors are replaced with pools of lava which Samus may fall into after getting hit by the many projectiles in the room, therefore greater care is needed at this point. After destroying the final Zebetite, Samus can use the space it occupied to begin firing directly at Mother Brain. The front of her glass tank will break after the first Missile and leave her exposed to all following damage. Mother Brain's cerebrum will gradually pulse faster as her health is depleted.

After Mother Brain explodes in an excessive light show, the self-destruct sequence triggers and Samus must escape Tourian to the surface of Zebes.

In the FDS version, there is less slowdown in the Command Center caused by the massive quantities of sprites onscreen. Aside from this, the only difference with the battle itself is how much of Mother Brain's control capsule gets shattered when shot with a Missile: in the NES, only the central portion breaks open while the FDS removes the entire bottom half, fully exposing her face and trunk-like cable that connects her to the bottom of her tank. While the latter version may give the impression that this exposed area can be shot at point blank range by Samus when standing directly on Mother Brain's base, this part of her body is actually invulnerable. Therefore, Samus's most advantageous position is still the empty space left behind by the last Zebetite, as it lines up her Missiles with the Mother Brain's only weakpoint: her frontal lobes.

Metroid: Zero Mission[]

In the remake, Mother Brain plays the same role (besides no longer being the game's true final boss). She also makes two appearances prior to her boss battle: first in the game's introduction where Samus mentions her as a prime target, and later on she is seen observing Samus's progress in a cutscene that plays during the first elevator to Norfair.

The first half of the Mother Brain gauntlet, which consists of reaching Mother Brain's location, remains nearly identical to the original game's except for minor alterations, such as a reduction in the number of defenses and the Rinkas dropping health and ammo when destroyed. The room has only 12 Cannons, 12 Rinka generators, and 4 Zebetites present this time around.

Upon reaching Mother Brain, the battle begins to differ significantly: Samus gets locked into the last segment of the corridor with no means of going back. This segment has two small platforms over a large pool of lava, two Rinka generators and two Cannons. The Space Pirate leader's glass tank requires 20 Missiles (or 4 Super Missiles) to shatter, and her weakpoint is her single eye, itself taking 35 missiles, that can be targeted if Samus crouches while firing. Additionally, Mother Brain can now directly attack by gathering energy into her body to release a brain blast from her eye; when charging the blast, the eyeball recedes back into her body and is protected by several layers of flesh. This attack is used whenever Samus inflicts a set amount of damage or whenever Samus falls below Mother Brain's sight and the former returns to the platforms for a second after falling. The blast is capable of blocking all shots fired and can deliver consecutive damage in a row if Samus is struck from the front of the blast. The Screw Attack makes this battle slightly less troublesome as it can destroy the Cannon's projectiles and any Rinkas in the way. It is possible for Samus to bunker in the top-right corner of the battle area, on top of a Cannon. From there, Samus can fire aerial diagonal shots at Mother Brain, though the Rinkas still pose a threat as they can push Samus off the Cannon. Samus cannot hang on a Cannon square. It is also possible for Samus to stand on the very edge of the glass container next to Mother Brain, taking care not to touch the villain directly. Doing so can allow Samus to simply Morph Ball under the brain blasts and fire point blank at Mother Brain, leaving only active Rinkas to worry about.

In Normal Mode, Mother Brain's eye will close each time it receives a total of 5 Missile hits. In Hard Mode, the eye will close for every three Missiles received. A Super Missile automatically closes the eye with each hit and will reset the eye's normal Missile counter. This allows Samus to maximize damage output by using a certain amount of Missiles before using a Super Missile all before reaching the maximum damage limit the eye would normally close on. An invisible force blocks Samus from going behind Mother Brain at all times. A glitch may sometimes occur where the chamber fails to lock, allowing Samus to backtrack out of the room at any time.

Metroid Prime[]

The game's instruction manual describes the events that led to the destruction of Mother Brain in the original Metroid and Zero Mission. It is also stated that some time after Samus left planet Zebes, Space Pirate survivors who were in orbit during the former's assault on the planet began to rebuild their headquarters as well as resuscitate Mother Brain and her two sub-commanders, Ridley and Kraid. Mother Brain would not be seen or directly mentioned again throughout the entire Prime series and High Command leads the Space Pirates in her absence.

Mother Brain was also going to be mentioned in an unused dialogue in the opening:

Ten years ago, below the surface of Planet Zebes, the mercenaries known as "Space Pirates" were defeated by interstellar bounty hunter Samus Aran. Descending to the very core of the pirate stronghold, Samus exterminated the energy based parasites called "Metroids" and defeated Mother Brain, the leader of the pirate horde.

But the Space Pirates were far from finished. Several pirate research vessels were orbiting Zebes while Samus fought on the surface below.

After the fall of Mother Brain, the ships escaped, with the hopes of finding enough resources to rebuild their forces and take their revenge.

After discovering a possible pirate colony on planet Tallon IV, Samus has again prepared for war, hoping to end the Pirate threat forever.

—Unused introductory monologue.

Metroid: Samus Returns[]

Against all odds, Samus Aran eradicated the Metroids on Zebes and defeated Mother Brain, the leader of the Space Pirates. And so their sinister plans were thwarted... for a time.

Metroid: Samus Returns introduction

Metroid Samus Returns Mother Brain battle

Flashback of Samus fighting Mother Brain and the Metroid larvae in Tourian during her Zero Mission

While Mother Brain does not physically appear in Samus Returns, she makes a brief cameo along with Metroid larvae, Rinkas, and Cannons in the game's introduction in a panel recounting the battle during Samus's Zero Mission. As a result of misuse of the Metroids by Mother Brain and the Space Pirates, the Federation decided to send Samus to SR388 to exterminate the species outright.

It can be assumed that the reconstructed Mother Brain gave Proteus Ridley the order to interfere with Samus's mission and to capture at least one Metroid specimen.

Super Metroid[]

Mother Brain is first seen in a short flashback of the battle that took place during Samus's previous mission on Zebes. Afterwards, the villain is not seen again until the game's final boss battle.

The first part of the final conflict remains roughly the same as prior battles: reach Mother Brain while overcoming her security defenses consisting of 12 Cannons, 11 Rinka generators and 4 destructible Zebetites. The lava is initially absent, but the entire corridor will shake as the former is released into the lower floors. The front of the Control Capsule will shatter after severl Missiles or Super Missiles while the rest breaks down as Samus inflicts damage to Mother Brain. Unlike Zero Mission, Mother Brain can be fired upon any exposed area of her body, making this part of the battle more akin to the original Metroid. Her body is not only vulnerable to concussive weaponry, but also to the properties of the Charge Beam. The Pirate leader never opens her eye or mouth, merely shaking and groaning with every hit.

To Samus's surprise, the battle concludes faster than their previous confrontation, leading to the collapse of the structure Mother Brain was on as her body falls to ground while turning pale. Additionally, the gun barrels of the nearby Cannons explode, the lava is drained from the room and the path behind Samus closes. A tense moment of silence passes before Mother Brain suddenly rises off the ground, now connected to a sitting bipedal body that was seemingly hidden underground.

As the body stands up and Mother Brain's color reverts back to normal, she finally opens her eye and roars at Samus, marking the start of the battle's second phase.

Mother Brain SM Flashback

Mother Brain in the flashback at the beginning of Super Metroid.

No longer an immobile being that largely relies on security systems, Mother Brain uses her new body to its maximum extent. She closes the distance between herself and Samus in an attempt to corner the latter while unleashing projectiles from her mouth, hands and eye. Her body is invulnerable save for the "head" and attacking the latter will push her back, giving room to avoid her attacks. After a set amount of direct hits, Mother Brain will gather energy into her cerebrum for her most devastating weapon: the Laser Brain Attack which can neither be stopped nor dodged. If Samus has a high amount of health following the attack, the A.I will fire additional shots from her weapon until the former is unable to move, prompting Mother Brain to approach and use regular attacks to drop her health under 100 units of energy. The Pirate leader will then roar triumphantly before charging the Laser Brain Attack once more, intending to finish off Samus.

Before the shot is fired, the mutated Metroid that imprinted onto Samus flies in and latches onto Mother Brain. As it absorbs her energy, she will thrash violently until she falters and her entire body becomes a husk. The Metroid then latches onto the still-crippled Samus and transfers the absorbed energy into her. Shockingly, Mother Brain somehow resurrects herself and, visibly injured and unable to use her Laser Brain Attack, she angrily attacks the Metroid as it heals Samus. Eventually, Mother Brain deals a killing blow as it tries to attack her again. At that moment, Samus manages to stand up and begins firing the Hyper Beam, revealing that the Metroid stole Mother Brain's weapon and was partly used to forge Samus's own. She uses it to overpower her enemy and avenge her fallen "child", causing the A.I to yell in agony with every hit until the mobile body explodes. Mother Brain then falls to the ground, once more turning into a husk as she weakly opens her eye and mouth before crumbling to dust. Afterwards, a Countdown starts, this time to obliterate the entire planet of Zebes.

As of Super Metroid, the original Mother Brain created by the Chozo has been completely eradicated, and her resurrection is unlikely.

Super Metroid comic[]

"What's the matter? All I said was that Komaytos look like little Metr-"

Non-canon warning: This article or section contains information that may not be considered an official part of the Metroid series in the overall storyline by Nintendo.

Loosely based on the events of the game, Mother Brain tries to convince the baby that she was its mother, not Samus, but failed immensely. When Chief Hardy accidentally killed the baby, Samus was enraged. Believing that Mother Brain was its killer, Samus killed her. She spent time in her body a bit more than in the game, as she was using her body when attempting to convince the baby that she was its mom.

Non-canon warning: Non-canonical information ends here.

Metroid: Other M[]


Mother Brain in Metroid: Other M before slaying the baby Metroid.

A 3D version of the Final Conflict in Super Metroid is featured in the Metroid: Other M opening cutscene. The baby carries Samus into the air before being destroyed by the Laser Brain Attack. It then explodes over Samus into many small particles, resembling a rain of snow. Mother Brain then closes in to destroy Samus, who whispers "Mother! Time to go..." and finishes her off with the Hyper Beam before escaping Zebes.

Mother Brain CA

Metroid: Other M Gallery Mode

Later in the game, when Samus learns that Metroids were being propagated on the BOTTLE SHIP, she wonders out loud if the scientists recreated Mother Brain. A female scientist clarifies that they modeled a large, featureless brain after the Pirate leader, codenamed "MB" and programmed it to reproduce the Mother Brain's thought processes.

MB first form

MB's original brain form

Near the endgame, another survivor reveals that the scientist Samus encountered before was actually MB in an android form. MB's first form (the aforementioned brain) was originally used to control the Space Pirate special-forces unit, while her second humanoid form was created in an attempt to control the ship's propagated Metroids. However, MB went rogue and seemingly manifested a malevolent personality akin to Mother Brain's. The brain MB is destroyed by Adam Malkovich when he triggered Sector Zero's self-destruct sequence, and the android MB is ultimately killed by the arriving Galactic Federation Army.

Metroid Dread[]

MD Ending Rewards 03 - SM

Mother Brain in the best Normal Mode Ending Reward.

Mother Brain herself is depicted within the main game in a fresco that can be found in an elevator room connecting Ferenia to Dairon. The same hieroglyphs appear to depict a battle between the Mawkin and the Zebesians. Mother Brain is positioned on the Mawkin's side of the fresco, which may imply that this event took place prior to Mother Brain betraying the Chozo. Aside from this, she is shown in the Ending Reward that is unlocked when the game is completed on Normal Mode in under four hours, and she also appears in the respective images rewarded for unlocking all Ending Rewards and Chozo Archives.


Original body[]


Mother Brain in her shattered Control Capsule

Mother Brain's original body, first seen in Metroid: Zero Mission, is the one most often shown in media within and outside the Metroid series. She resembles an exposed human brain, but gargantuan in size and with a single eyeball located below her cerebral hemispheres which is normally hidden beneath folds of flesh or behind eyelids. This eye's pupil can constrict to a slit or dilate to a circle, similar to a reptile. Her body is also covered in metal implants, such as the conical spikes protruding from the flesh of her pulsing cerebrum, and thick tubes or pipes situated near her cerebellum.

Below Mother Brain's body is a mass of machinery with cables and wires, some of which connect directly into her platform. She is contained within a sealed glass tank known as a Control Capsule that protects her from external attacks and other outside elements; this, coupled with the machinery underneath her body leaves her completely immobile. It can be assumed that her capsule is also connected to a life-support system, as it has been stated that Mother Brain requires constant supply of Zebetites to remain alive [5].

Reconstructed body[]

Super mother

Mother Brain's 1st form

Mother Brain's body is reconstructed in Super Metroid, gaining some slight differences. The largest divergence is the presence of a facial skeleton beneath her eyeball, giving her jaws with sharp teeth, a tongue, salival glands, and tan-colored skin. The sides of her face are embedded with metal pipes, and wires extend from the top and bottom of her body to connect to the devices around her Control Capsule. Other changes are subtle: her spikes are noticeably longer, and her brain tissue is more orange than red (though it darkens to red following the Baby's attack). Most of these changes appear to have been made to allow compatibility with a new combat body.

MotherBrain drool

Her mobile form appears to be based on Chozo technology.

Once Mother Brain's Control Capsule is compromised, she is able to connect to a giant bipedal combat body hidden below the floor. It is vaguely humanoid, featuring arms and legs, as well as a sagging pot-belly and a skintight exoskeleton on her upper torso. It appears to be comprised of both machine and organic tissue, with vague similarities to a Torizo. When connected, Mother Brain is situated at the top of the neck to function as the "head" of the body. With this bipdeal posture, she becomes the second tallest creature on Zebes, second to Kraid. When in use, Mother Brain produces grotesque amounts of saliva and emits purple smoke from her mouth and/or from the circuitry on the sides of her face.

Metroid: Other M features a flashback of Mother Brain in this combat form. The body's design is slightly altered, with a slimmer, skeletal design and longer arms, while Mother Brain herself appears smaller in proportion.

NES/Famicom version[]

Metroid Boss Mother Brain

Mother in the first Metroid game

Mother Brain's very first appearance in the NES/Famicom Metroid featured a "face" instead of the single eyeball that would be established in later games. She had a pair of sneering white eyes, a nose-like protuberance, and two tusks around a metal cable connected to the base below her, making her vaguely resemble an elephant. This version of Mother Brain became non-canon as early as Super Metroid, in which the intro sequence featured a flashback of the final battle from the NES/Famicom game with an updated design.



Mother Brain during a cutscene in Zero Mission.

Very little was known of Mother Brain within the games, although it was initially believed that her origins were deeply connected with the Space Pirates: in-game texts, instruction manuals and players' guides described her as their leader, being the perpetrator of their malicious plans and controlling all operations on Zebes. In particular, she is stated to have come up with the idea of using the highly dangerous Metroids as bioweapons against galactic society. Her location in Tourian and the surrounding security emphasized her role of not only being the top ranking member of the pirates, but also as a vital piece of equipment, as her defeat initiates Tourian's self-destruct sequence.

Her personality was an even greater mystery, with only her immobile and mostly expressionless form giving, intentionally or not, the impression of a very cold disposition. Her behavior in Super Metroid indicated she was highly cunning; anticipating a repeat of her previous encounter with Samus, she lured her into a false sense of victory before emerging with the new mobile body, cornering and overwhelming her foe with massive firepower. In addition, after knocking enough of Samus's health out that the latter could no longer even stand up, Mother Brain also was shown to repeatedly toy with Samus by hitting her with her more minor attacks until she was at an inch of life left before deciding to use the Laser Brain Attack a final time with a triumphant roar, hinting at a more sadistic nature. Despite these calculated moves however, there was evidence of Mother Brain losing control during spontaneous bursts of emotions when, in a fit of rage, she foiled her own plans by destroying the last living Metroid after the creature saved Samus's life, as well as panic when Samus attacks her in retaliation by trying to use every attack in her disposal in an erratic manner.

Although Mother Brain claims in the manga that she was following her directive per what the Chozo intended, it is heavily implied that she truly desired to have full control of the universe for its own sake. Furthermore, it comes to light that Mother Brain is in fact using the Space Pirates to further her own goals, referring to them and all other beings in existence as simple beasts. She intends on having her forces fight the Galactic Federation until both organizations become sufficiently crippled, at which point she will "cradle" the survivors to "sleep" and, after resetting the universe to zero, help them reach an intellectual level that she deems worthy of life. Thus, achieving her goal of bringing true order. She also plans on using an "evolved" form of the Metroid species to secure her dominion over all life.

It is to be noted that her means and views on "order" had noticeable similarities to the renegade Chozo Raven Beak's "Power is Everything" philosophy of bringing order through warfare. This implies that her going renegade may have been influenced to some degree by Raven Beak, either through direct programming or merely through inspiration.


Mother Brain's role in the Space Pirates has been mostly vague in the Metroid series. There is debate as to whether she or Ridley is the supreme leader of the Pirates, with this question growing more confusing with the mention of High Command from the Metroid Prime games.


Mother Brain detects Samus's presence

According to Super Metroid's manual, Metroid: Zero Mission's manual, and the official manga, Ridley is the general of the Space Pirates while Mother Brain is the biological computer which controls Zebes' defenses. However, Metroid's manual, Metroid Fusion's manual, Metroid: Zero Mission's game box, the Super Metroid Nintendo Power comic, and Super Metroid's in-game introduction refer to Mother Brain as the leader of the Space Pirates, with Metroid's manual saying that Ridley is controlled by Mother Brain. The manga later retcons this to rectify any confusion by stating that Mother Brain took over as one of the pirates' leaders, while keeping Ridley in his former position. Additionally, her referring to Ridley and the other Space Pirates as "simple beasts" might help explain the previous statement of Mother Brain controlling Ridley.

The Space Pirate Data in Metroid Prime refers to a High Command that commands the Space Pirates, which included ordering Ridley to be reconstructed. Whether or not Ridley is part of High Command is unclear; he may be the Pirate general, answering to High Command and/or Mother Brain. The group's presence has only been mentioned during the time of Mother Brain's inactivity and as such, High Command itself may or may not be subservient to her.

A profile of Ridley in the August 2002 issue of IGN Unplugged describes Ridley as a "Slave to Mother Brain and the Space Pirates".[6]

Media outside of the Metroid series often describe Ridley as the highest ranking member of the Space Pirates. Some of the latest Metroid games, such as Metroid: Other M (its instruction manual, official website and in-game) along with the prologue cutscene in Metroid: Samus Returns, state that Mother Brain is the true leader.

Though speculative, a way of rectifying all this is that Mother Brain is more of a separate antagonist who's allied with the Space Pirates and is viewed by them as extremely valuable to their conquest designs. So although Mother Brain is afforded great authority as the guiding strategist, to the degree that the Pirates defer to her, she is not truly their leader, which is a role taken by High Command. The science team on Tallon IV sought Space Pirate domination and showed no subservience or reverence for Mother Brain beyond her reconstruction being a priority. A lack of reverence towards her is also seen with the Pirates stationed on Aether. Similarly, Mother Brain had no regard for the Pirates and viewed them as disposable tools.


As a sentient, organic super computer built by the advanced Chozo, Mother Brain is capable of performing an extremely wide range of complex operations and algorithms of unimaginable magnitude. Connected directly to Tourian, she oversees the planet's many technological functions and security systems, along with archiving vast amounts of information and historical data, making her an invaluable intellectual support to whomever she allies herself with. Due to her inability to move under normal circumstances, she resorts to using a small, floating spherical monitor in the manga to observe, accompany, and converse with individuals outside of her physical body's location. This monitor is not her only means to observe the outside world however, and she likely can see through any type of surveillance tech connected to the vast system on Zebes. This amount of control, coupled with her self-awareness and genius intelligence, is potentially what led to Mother Brain going rogue.

Several sources in past media imply that Mother Brain can influence/control her Pirate forces and wildlife with telepathy. This would explain why a large portion of the native flora and fauna on Zebes are highly aggressive toward Samus in the games, as the Pirate leader is directing them against her. Indeed, the manga has Samus directly accuse the A.I of this act. A cutscene in Zero Mission shows Mother Brain observing Samus in a moving elevator seemingly with no surveillance camera inside, potentially hinting at the former using her telepathy to see across vast distances.

The Metroid species are seemingly one of the few organisms that are immune to Mother Brain's telepathy. Events in Zero Mission and Super Metroid show the titular creatures attacking Space Pirates, including Mother Brain herself. The Metroid Prime series provide further proof with logbook entries stating that the Pirates have yet to develop any method of making their Metroid specimens obey orders. Strangely, Samus claims in Other M that the Pirate leader is the only thing that can control them, yet despite her statement and a copy of Mother Brain's AI active during the game's events, all Metroids within the BOTTLE SHIP are kept in enclosed locations and containers except for an escaped infant, directly implying the species are still uncontrollable.

The first mention of Mother Brain's psionic abilities in media appeared in the non-canon Nintendo Comic System story: The Coming of a Hero in which she is, ironically, shown to display mental control over the Metroids. In the Super Metroid comic, the last Metroid rejected Mother Brain as it believed Samus was its mother, an act that further reinforces her inability to control the deadly species. Although her cameo appearance in Metroid: Samus Returns features a summary of Zero Mission with an image that implies she is directing nearby Metroids to attack Samus, it is important to note this is not an accurate depiction of events but merely a dramatized rendition; in the actual game, Mother Brain and her Metroid specimens were never in the same room.

Aside from her telepathy and the skills relating to her status as a super-computer, she can control weapon systems linked to her network (wired or wirelessly) such as the Cannons and the manga's Work Robots equipped with flamethrowers. Mother Brain gains additional weapons once she connects to her mobile body via the machinery on her underside: massive physical strength, blue ringed beams and bombs which are both expelled through her mouth, as well as an explosive barrage unleashed from her hands. Finally, the Pirate leader displays the ability to shoot a variety of beam projectiles out of her single eye, the most notable being the Brain blast and the devastating Laser Brain Attack, though only the former seems to be an innate weapon due to all others being exclusively used after the appearance of her mobile body. On that note, the blue ringed beams were also shown to be potent enough to significantly wound a Big Metroid if not kill it outright.

Similar entities[]

Metroid Prime 3: Corruption[]


The future Aurora Unit complex.

The game features beings known as Aurora Units which have strong parallels to Mother Brain. Built by the Galactic Federation, these constructs are seemingly organic neuron masses encased in metal plates floating within a tank, making the AUs resemble giant brains confined in jars. They are used as super-computers to navigate in a large digital network and process enormous amounts of information, as well as keeping their users constantly up to date on current events. The Aurora Units were first introduced in a preview trailer that also showcased Federation blueprints for a "future Aurora complex" where an AU is located in a room nearly identical to Mother Brain's Command Center built by Zebesians in Super Metroid.

During the events of Metroid Prime 3, Aurora Unit 217 is able to link up Federation and Chozo information databases, akin to what Mother Brain is capable of in the prequel manga. The final boss, Aurora Unit 313, is an AU gone rogue: following its change of personality, the Space Pirates seemingly granted it additional attributes that correspond to Mother Brain's, such as nearby turrets firing Rinka-like projectiles, an ocular organ-like device that fires a purple laser, and a cable supporting 313 that foreshadows Mother Brain's neck in Super Metroid. The Aurora Unit 313 theme is an arrangement of Darkness, Dark Samus' theme, arranged to resemble Mother Brain's theme in Zero Mission. Finally, there is an unused Federation log for Aurora Unit 242 that indirectly references Mother Brain, as the character Fleet Admiral Castor Dane was mentioned in the log to be very critical of Aurora Unit 242's nickname of "Other Brain" given by veteran crew members.

While there is currently no official word on a possible connection between Mother Brain and the Aurora Units, a few theories propose that either the former is actually a rogue Aurora Unit (of Chozo origin), or the AUs were modelled after her.

Metroid Prime: Federation Force[]

Main article: Master Brain

The final boss of the game is Master Brain, a massive brain-like organism contained within a pink cylindrical force field. Its name and the numerous Grim-Class Turrets installed in its room are reminiscent of Mother Brain and her Cannons. Not much is known about this entity other than it is directly affiliated with the Space Pirates and is visually more mechanical than organic, giving it a closer resemblance to an Aurora Unit.

Metroid Dread[]

Main article: Central Unit

Throughout planet ZDR are giant brain organisms called Central Units. They each feature a single eyeball which, along with their body, are initially encased in metal plating that gets removed when Samus inflicts sufficient damage to them; while encased, the eye has a striking resemblance to Mother Brain's monitor from the prequel manga. Like the Space Pirate leader's immobile form, the CUs do not attack by themselves but instead rely on the Rinkas and Central Unit Cannons present in their rooms.

Additionally, whenever Samus uses her Metroid powers to leech energy from a defeated CU, the energy is converted into a temporary but powerful weapon used against otherwise indestructible foes. This parallels Mother Brain's final moments in Super Metroid when her energy is taken by the last Metroid and transferred to Samus, creating the Hyper Beam that killed the unstoppable antagonist before the weapon seemingly vanished later on.

All of the above, along with the Central Units being found on a planet belonging to a Chozo tribe, strongly imply a connection to Mother Brain. It is possible that the Central Units were modelled after her.

Appearances in other media[]

"What's the matter? All I said was that Komaytos look like little Metr-"

Non-canon warning: This article or section contains information that may not be considered an official part of the Metroid series in the overall storyline by Nintendo.
  • A microgame called Metroid in WarioWare, Inc.: Mega MicroGame$! and WarioWare, Inc.: Mega PartyGame$! re-enacts the fight between Samus and Mother Brain from Metroid. It is slightly different than the original fight, but mostly the same. It also seemed to retain the siren system from the Famicom Disk System version.
  • Mother Brain is mentioned in Super Mario RPG: Legend of the Seven Stars. If Mario returns to the Mushroom Kingdom castle before going off to Land's End, Samus will be sleeping in the palace's guest room bed, and if talked to, will say that she is resting up for Mother Brain. It is to be noted that this was only the case in the English localization, as in the Japanese version, she actually references the tagline for Metroid II, "Metroid... Omoroido!"
  • In the Nintendo Comics System-published story Duh Stoopid Bomb! which contains characters from the Mario series, Mother Brain's name appears on a list of people who think King Toadstool is dumb.
  • Mother Brain appears in the background of level 12 in Marathon Mode in Tetris DS, which is Metroid-themed.
  • Mother Brain and her usage of Metroids is given an indirect reference in Animal Crossing: New Leaf via the Fortune Cookie that supplies the player with a Metroid, where the text states "Wise men say the brain is a terrible thing to waste."
  • Mother Brain appears as a boss in I Wanna Be the Guy, where she is guarded by Rinkas, Metroids, and Zebetites.

Captain N: The Game Master[]


Mother Brain as she appears in Captain N: The Game Master

In the TV series Captain N: The Game Master, Mother Brain is the main antagonist. She is portrayed as a supervillain with a human-like face, bearing little resemblance to her actual appearance ingame. This depiction of Mother Brain also appeared in the Nintendo Comics System and Captain N comic book series.

Mother Brain's voice in the television series was provided by the late Levi Stubbs of the The Four Tops. Stubbs had previously played a similar character, Audrey II, in the 1986 version of Little Shop of Horrors. Like Audrey II, Mother Brain has a feisty and flamboyant personality. She is very power-hungry but also incompetent and easily frustrated by her slow-witted assistants, King Hippo and the Eggplant Wizard. In the French dub, she is voiced by Évelyne Grandjean, and called Mama Cervelas.

One comic called Nervous Meltdown depicted Mother Brain's self-perception within her consciousness.

Super Smash Bros.[]

In Super Smash Bros. Brawl, Mother Brain appears as a sticker, using artwork from Zero Mission. She can be equipped to any fighter and grants Flinch Resistance.

Ssb4 mother brain

Mother Brain as an Assist Trophy in Super Smash Bros. for Wii U.

On February 7th, 2014, Masahiro Sakurai posted an image on Miiverse and confirmed that Mother Brain would appear as an Assist Trophy in Super Smash Bros. for Nintendo 3DS and Wii U. Her appearance is taken from Zero Mission, where she appears onstage in her Control Capsule with Rinkas flying around. She uses the Laser Brain Attack from Super Metroid, possessing a quicker firing rate but shorter range. Use of the Attack causes the Capsule to break. Mother Brain charges and fires the beam (which retains its sound effect from Super Metroid) twice, aiming it toward the ground. Mother Brain can also turn in her capsule to aim at opponents accordingly. Before she disappears, she seems to bounce, or "nod" at the summoning character. Mother Brain can be killed, with her trophy description quipping that it will not trigger a countdown as tradition.

SSB Ultimate Samus vs Mother Brain

Mother Brain in Ultimate

Mother Brain returns as an Assist Trophy in Super Smash Bros. Ultimate. Additionally, she appears as an Ace class Primary Spirit who can be equipped to fighters to provide a stat boost. Much like the Sticker from Brawl, she uses her artwork from Zero Mission. She is a Shield type, giving her advantage over Attack types but disadvantage against Grab types.

Like all other Primary Spirits, she can be leveled up through battle experience, Dojo training, or snack eating; upon reaching Level 99, she can be enhanced to Mother Brain (2nd Form), using artwork of her final form from Super Metroid. This resets her level to 1, but promotes her class to Legend and grants her the Giant skill: at the start of a battle, any fighter who has Mother Brain (2nd Form) equipped will be giant.

Mother Brain's Spirit can be unlocked in the World of Light Adventure Mode, where she appears in the Final Battle as one of Dharkon's Spirits. She can also randomly appear on the Spirit Board. In Spirit Battles, Mother Brain possesses a Dark Samus Puppet Fighter in her dark red costume. Dark Samus favors using her Charge Shot, and she is joined by Mother Brain as an Assist Trophy. The battle takes place on the Omega Form of Planet Zebes: Brinstar Depths, with Escape as the background music (presumably referencing the theme's use after beating Mother Brain in Metroid and Zero Mission). All combatants have increased power when using energy attacks.

Non-canon warning: Non-canonical information ends here.

Official data[]


Super Metroid storyboard

Metroid manual[]

Mother Brain
"Mother Brain lies in the central base of the fortress planet Zebes, the home of the space pirates. Its aim is to cultivate Metroid[7] to multiply and conquer space. Zeebetite is its energy source. You have to discover Mother Brain's weak point before you can launch a missile attack. When hit, it makes a shrieking noise."

Virtual Console retranslation[]

Mother Brain
"Mother Brain lies in the center of the planet Zebes. She plans to cultivate the Metroids and use them to conquer the universe. It's claimed that she is a massive mechanical life-form, but nobody knows for sure…"

Nintendo Power Volume 29[]

"As the controlling force of the Metroid and the despoiler of the planet, Mother Brain is one of the most dangerous beings in the galaxy. You'll need full missiles and six energy tanks, because you're bound to take a lot of damage while attacking this monstrosity from close range.
Mother Brain's only weakness is in the middle of the glass case, and only missiles will damage it. Attack from the platform left by the final Zebetite, making sure you fall backward when struck by Rinkas. Keep moving to avoid damage. There's one other attack option. Jump against the case itself and push left, then pump missiles into the opening."

The Official Nintendo Player's Guide[]

"This is the backbone of the fortress planet Zebes, and it is the one determined to multiply Metroid. It is Samus’ ultimate target. In order to destroy it, over 30 continuous missile shots are required."

Super Metroid interview[]

Interviewer: Huh? Made it dirty?
Mashimo: Apparently, the characters I drew were fairly cute. Characters like Crocomire were so charming that when they were killed, the player would feel sad about them.
Osawa: He wanted to them to look like Fujiko Fujio's work! Then Yamane came into the picture.
Mashimo: When that happened, the characters became harsher so that the player could defeat them.
Osawa: Fujiko Fujio became Hino Hideshi!* (Laughs)
Sakamoto: Like Mother Brain!
Osawa: At first, I drew her. Then, I made the character look like an old lady living in my apartment complex. (Laughs)
Mashimo: I wanted to see a shopping bag hanging from her hands.
Osawa: Then Yamane-sensei appeared.
Mashimo: After that, saliva dribbled down, she spit out foul breath, and she was filthy.
Sakamoto: Well it wasn't static as the rest was terrible, so we cut down on the amount of drool. Anyhow, in the final version, there was a moderate amount of drool. (Laughs)

Super Metroid Players' Guide[]

Mixing It With Mother Brain (page 70)
"The perpetrator of all the trouble. Mother Brain is at the very core of Zebes, controlling all the operations on and around the planet. It will take every ounce of strength, courage and determination to make it past this heinous enemy.
Your weapons should be numerous by now, but you'll need to make a swift decision on which one to use. Will it be the super missiles or the power bombs? How about one of the beams? You're on your own now - few adventurers have ever seen the Mother Brain, let alone lived to tell the tale. But you've got this far so don't give up now!"

Nintendo Power Volume 95[]

"Mother Brain waits behind a shield of glass and a barricade of Zebetites. Missiles are the key. Bring as many as you can to blast both the Zebetites (the blocking columns) and Mother Brain's enclosure."
"There's more to the Mother Brain than a brain. After you tick her off, she transforms into a moving menace. Be prepared to take some damage while attacking her head with Super Missiles and Missiles. Shoot at a 45-degree angle to keep your distance."

Metroid FAQ (Metroid Zero Mission Official Site)[]

Game Informer 300th issue cover

Cover for the 300th issue of Game Informer.

"If the Chozo made Mother Brain, why is she so dangerous?"
Yoshio Sakamoto: "Mother Brain was not originally dangerous, and was an indispensable artificial intelligence that served as the center of the advanced Chozo civilization. However, as an extremely superior standalone AI, Mother Brain sprouted dangerous thoughts and went berserk."

Captain N: The Game Master – The Complete Series[]

The Forces of Chaos[]

"Mother Brain is part grotesquely enlarged human brain, part souped-up bionic support system, and all evil. Every electrical device on Metroid, from the robot workers in the airlocks to the TV monitors and toasters, has been wired to do her bidding. In her high-tech nest at the center of the planet, Mother Brain spins her schemes and directs the Forces of Chaos' grand conspiracy. "

The Triforce is as good as mine! Once I get rid of you potato heads, that is.

—Mother Brain

Brawl Sticker[]

Metroid: Other M Art Folio[]

Mother Brain and the Baby Metroid[]

"A dream - I was reliving the tragic moments of my recent past. The Baby Metroid that had emerged from its egg in front of me so long ago was protecting me from the assault of Mother Brain. It would sacrifice its life to save me, and in doing so, give me the power of the Hyper Beam that would spell Mother Brain's doom."

Miiverse post[]

"Pic of the day. Housed within the Control Capsule! Protected by Rinkas! Eyeball armed with a Laser Brain Attack!! The massive Assist Trophy Mother Brain joins the collection!!"

Super Smash Bros. for Nintendo 3DS and Wii U website[]

"Mother Brain from the Metroid series is an enormous Assist Trophy that fires vertically tracking laser rays. Fighters caught in the rays will rack up numerous hits and damage, so it's better not to be in front of her. By the way, it's possible to defeat Mother Brain by attacking her."

Super Smash Bros. for Nintendo 3DS Trophy[]


3DS Trophy.

"Hailing from the Metroid series, this evil boss resides on the planet Zebes. When she appears in Smash Bros., she attacks with energy projectiles and a beam from her eye. It's actually possible to defeat her, and for once doing so won't start a self-destruct sequence."
"A mainstay of the Metroid series and the final boss Samus faces on Planet Zebes. In this game, she grows to a gargantuan size and fires all sorts of energy blasts at you. Good news: you can beat her! Better news: doing so won't trigger a self-destruct sequence forcing you to make your escape!"

Super Smash Bros. for Nintendo 3DS and Wii U Tips[]

"Attack Mother Brain to defeat her! The glass around her will shatter after she fires lasers—that's your chance to strike!"

"Mother Brain will fire ring-shaped projectiles called Rinkas from off-screen. These are energy based, so they can be absorbed or reflected."

"Mother Brain will send colorful lasers shooting up and down the screen. They can't be absorbed or reflected, so you'll have to just avoid them!"

"It's totally fine to use Mother Brain to shield yourself from the attacks of your rivals."

Tips (Super Smash Bros. Ultimate)[]

Assist Trophy: Mother Brain"Attack Mother Brain to defeat her! The glass around her will shatter after she fires lasers—that's your chance to strike!"

Assist Trophy: Mother Brain's Rinkas"Mother Brain will fire ring-shaped projectiles called Rinkas from off-screen. These are energy based, so they can be absorbed or reflected."

Assist Trophy: Mother Brain's Lasers"Mother Brain will send colorful lasers shooting up and down the screen. They can't be absorbed or reflected, so you'll have to just avoid them!"

Assist Trophy: Mother Brain as a Shield"It's totally fine to use Mother Brain to shield yourself from the attacks of your rivals."

List of appearances[]

Musical themes[]

This is the theme of Mother Brain in Metroid: [1]

This is the theme of Mother Brain in Super Metroid: [2]

This is the theme of Mother Brain in Metroid: Zero Mission: [3]

Development notes[]

Mother Brain might be a play on the part for computers, the Motherboard, as she is connected to a board-like structure. Alternatively, since the Metroid series was inspired by the Alien movies as speculated, Mother Brain's name may have derived from the main computer of the Nostromo, "Mother".

Although Mother Brain was shown talking in the Magazine Z manga, she was only shown making vocalizations in Super Metroid and Other M (not counting MB), both merely depicting her roaring incomprehensibly while she was using her body. In Super Metroid, her roars were taken directly from Mothra from the Godzilla franchise, albeit slowed down.


  • Mother Brain has been very well-received by the gaming community, often considered one of the best video game villains:
    • In a PC World article, Mother Brain was voted as #6 of the top 47 "most diabolical videogame villains of all time."[8]
    • In Game Informer magazine, Mother Brain was rated #2 on their "Best Boss Fights Of All Time" list.
  • Why Zebes exploded following Mother Brain's death in Super Metroid and not in Metroid/Zero Mission was never explained. It is possible that as she was being repaired from her first defeat, she became symbolically linked to the planet, similar to how Aurora Unit 313 was linked to planet Phaaze, consequently starting a chain reaction when killed.
  • In Super Metroid, when attacked by the baby, Mother Brain crouches in a pose similar to the Chozo Statues. This may hint that the Space Pirates may have used Chozo technology to build Mother Brain's mechanical body, or it may simply refer to the fact that Mother Brain is Chozo technology.
  • Characters named Mother Brain also appear in Chrono Trigger, Phantasy Star II, and Blaster Master Zero.
  • Mother Brain is the only creature known to survive having all her energy apparently drained by a Metroid. Despite being reduced to a grayed lifeless husk, she seemingly "resurrects" herself moments later, though it may be related to her bio-mechanical nature.
  • Although Mother Brain's plans revolved around the exploitation of the last surviving Metroid in the galaxy and went through great lengths to acquire the creature, she appeared to have no qualms with killing it when it helped Samus, thus putting an end to her own plans. It can be interpreted that, in the climax of the battle, she was determined at killing the heavily wounded Samus above all else, as this act would remove the greatest threat to the Space Pirates' existence.
Mother Brain Lane
  • In the title sequence for the first Metroid, under the Emergency Orders segment, Mother Brain was described as "the mechanical life vein." This was a mistranslation of the term "mechanical life-form." The opening sequence for Metroid: Zero Mission features the corrected term.
  • Mother Brain's archetype inspired similar characters in later franchises, such as Phantasy Star, Chrono Trigger, and Final Fantasy.
  • Nintendo of America's headquarters in 2004 had a hallway called "Mother Brain Lane".[9]
  • In WarioWare, Inc.: Mega MicroGame$! and WarioWare, Inc.: Mega PartyGame$!, Mother Brain appears in a microgame called "Metroid" that recreates the battle between her and Samus in the first Metroid. It retained the siren system from the Famicom version, although being slightly different from the original battle.
  • In Contra: Operation Galuga, the game's final boss possesses a brain strongly reminiscent of Mother Brain. Further strengthening the resemblance is the fact that the brain fires Rinka shaped projectiles.


For artwork, see Mother Brain's Gallery.

References and footnotes[]

  1. ^ Metroid Prime manual
  2. ^ Metroid: Volume 2 pg. 79, as translated by Metroid Database
  3. ^ Metroid: Other M Chapter 1 - Opening Cutscene.
  4. ^ 'Madeline Bergman' (MB): "MB was the artificial intelligence originally developed to regenerate and control Space Pirate special forces. Because we wanted it to control these special forces through telepathy, we were forced to model its infrastructure after Mother Brain... Before long we started to see the viability of creating Metroid clones. Once we did... MB started to take on her current shape." - Metroid: Other M. 2010.
  5. ^ Metroid (game) manual
  6. ^ File:IGN Unplugged Issue 15 2002-08 US 0008.jpg
  7. ^ "Metroid" was originally both singular and plural.
  8. ^;338891934;pp;3
  9. ^ Nuyens, Jason. "Nintendo Enthusiast Summit 2004". Nsidr. November 10, 2004. Archived from the original on May 7, 2020. Retrieved April 26, 2023.