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Defective product… Me…?!! A defective product… You dare claim that I am defective…!!
~ Mother Brain.

Mother Brain (in Japanese: マザーブレイン, Mazā Burein) is the main antagonist of the Metroid series.

She is a cold artificial intelligence created by the Chozo, but turned against them when the Space Pirates and Ridley invaded Zebes. Mother Brain saw potential in the pirates and decided that with their help, she could bring true order to the universe by "resetting everything back to zero".



Mother Brain (Metroid NES)

Mother Brain in Metroid.

In Metroid, Mother Brain is the final boss in the last room of Tourian. She appears as a large brain within a glass stasis tank protected by Zebetite, Rinka, and turrets. The brain itself does not attack in any way after the tank is broken, unlike in the remake Metroid: Zero Mission. The Mother Brain also constantly regenerates life, much like the Zebetites, and the only way to tell how much damage she has taken is by how quickly she pulsates. If left alone, the pulsating will slow, and Mother Brain will heal herself. After Mother Brain has been destroyed, a self-destruct sequence begins, and Samus is forced to evacuate Zebes immediately. The manual for Metroid states that Mother Brain is the leader of the Space Pirates, which would mean Ridley is under her command, but not necessarily under total control.

Metroid: Zero Mission

In Metroid: Zero Mission, Samus's main objectives are to destroy all Metroid organisms on Zebes and defeat the biological super-computer, Mother Brain, as in the original Metroid. The re-rendered version of Mother Brain shares a slight resemblance to Super Metroid's take. She is located in the lowest area of Tourian and is protected by the classic Zebetites, Rinkas, and turrets. There have been some changes not only to Mother Brain's appearance but to her attacks and weaknesses as well. When her stasis tank is damaged and destroyed by Samus with several missiles (in the original NES game, it took but one missile to destroy it), Mother Brain starts countering by gathering energy into her brain and releasing it as a blast from her eye; this eye beam could be considered as a precursor/basis to the Hyper Beam the Mother Brain would have in her resurrected Super Metroid form. Unlike the NES Metroid and Super Metroid appearances, Samus can only wound the boss by firing directly at her eyeball.

Every time Samus hits the weak spot with either five missiles (three on Hard difficulty), one Super Missile, or drops into the lava in the room, Mother Brain closes her eye and resumes the beam attack as soon as Samus gets back up. Surprisingly, Mother Brain does not appear as the final boss of the game. After Mother Brain is defeated, Samus evacuates Tourian, takes flight and is ambushed by Space Pirates. After crash-landing on Zebes, Samus ends up having to board the Space Pirate Mother Ship in her Zero Suit with only an emergency pistol to defend herself.

Mother Brain (Metroid Zero Mission)

Mother Brain in Metroid: Zero Mission.

Unlike in Super Metroid, Mother Brain does not use a mechanical body and remains stationary. A revisit to Tourian after acquiring the Fully Powered Suit reveals a hidden chamber underneath Mother Brain's capsule that was also present in Super Metroid. This may indicate that her body was planned but not fully implemented or could have simply been a cache of life support systems connected underneath Mother Brain. The pools of lava have also been replaced by an extremely corrosive green chemical, the only substance in Zero Mission capable of harming Samus even while she is wearing the Gravity Suit.

Metroid Prime 3: Corruption

In Metroid Prime 3: Corruption, it is revealed that the Galactic Federation uses organic supercomputers known as Aurora Units, brain-like neuron masses in tanks that closely resemble Mother Brain. The Mother Brain was built by the Chozo, though the manga indicates that the Federation had some part in this as well as she was built to link the Federation and Chozo information databases, similar to the function of the Auroras. Also, the Metroid Prime 3: Corruption trailer for Aurora Units shows a "future Aurora complex" which bears a near-identical resemblance to the Mother Brain's room in Super Metroid.

Also, the final boss of the game, Aurora Unit 313, features many references to Mother Brain, such as its cannons firing red spheres that look similar to Rinka, the purple laser that bears resemblance to Mother Brain's beam attacks, and the cable that supports 313 that is similar to Mother Brain's neck in Super Metroid. The Aurora Unit 313 theme is an arrangement of Darkness, Dark Samus' theme, arranged in a way that resembles Mother Brain's theme in Zero Mission.

This along with the Federation's seemingly corrupt actions at the end of Metroid Fusion might indicate a deeper and darker meaning with the Aurora Units.

Super Metroid

Mother Brain (Super Metroid)

Mother Brain in Super Metroid.

In Super Metroid, similar to the original Metroid, Mother Brain is the final boss, found in the last room of Tourian. The battle against her remains the same initially. Once Samus defeats her, the actual brain itself falls to the ground and turns pale. After a short wait, she starts to rise up and is seen to be connected to a mechanical body, possibly built by the Space Pirates, indicating that she had learned from her mistakes in her last encounter with Samus.

Mother Brain uses a new weapon known as the Laser Brain Attack against Samus, which not only depletes an enormous amount of Energy Tanks, but also depletes Samus' Missile, Super Missile and Power Bomb ammo. When Mother Brain is about to finish her off, the Baby Metroid that Samus found on SR388 latches itself onto Mother Brain, absorbs her energy, apparently killing her, and restores Samus's health. An injured Mother Brain slowly reactivates and stands back up, and angrily attacks the Metroid as it covers Samus. As the Metroid lets go of her and lunges at Mother Brain once more, she delivers a killing blow, and the remains of the Baby fall over Samus.

Super Mother Brain (Super Metroid)

Mother Brain's alternate form in Super Metroid.

At that moment, Samus realizes that the Metroid was able to grant her the power of the Hyper Beam, which it stole from the Mother Brain. Enraged, Samus opens fire and defeats Mother Brain with her own beam attack. Afterward, Mother Brain's body is destroyed, causing her head to fall down and become pale. Mother Brain's head then weakly opens its mouth and finally turns to dust. Once Mother Brain dies, a Countdown starts, destined this time to end in the obliteration of the entire planet. Samus evacuates Zebes once again before it explodes with her on it. As of Super Metroid, Mother Brain has been eradicated from the universe, and resurrection is unlikely.

Metroid: Other M

Melissa Bergman

Melissa Bergman aka MB ("Mother Brain").

Main article: MB

Although Mother Brain herself only appears in a flashback at the beginning recapping her role in Super Metroid, her personality relies in the android Melissa Bergman (also known as MB), the main antagonist of Metroid: Other M.

MB perceives all life forms in the Bottle Ship not under her control, including the scientists, as a threat and controls the Desbrachians to attack in order for her to take over. She begins calling herself Madeline Bergman, the name of her former human friend and tries to manipulate Samus into believing that she is an ally. It is unknown if her actions influenced Ridley at all, who had been reborn in a new cloned body. It is possible that she may have been able to direct him upon his body being drained and his still-existing molecules being sucked into the Queen Metroid (which was destroyed by Samus, meaning his molecules would return to his drained body). Regardless, she is destroyed soon after the death of the Queen, being anticlimactically shot down by the Federation soldiers as soon as Samus takes care of the Desbrachians, thus destroying what may have been another Mother Brain. Ridley, however, was to be resurrected yet again in Metroid: Fusion.

It is possible that MB was under the manipulation of Phantoon, who shows up as the true final boss post-credits.

Metroid Prime: Federation Force

The main villain and final boss, Master Brain, appears as a variation to Mother Brain.

Metroid Manga

Mother Brain's flying monitor system. Mother Brain can monitor Zebes with its camera eye and communicate through it. In the Metroid manga, Mother Brain begins as an ally of the Chozo. The Chozo use her to keep track of data and reports.

When Samus disarms a number of Iona Faria that had been "corrupted" by the Space Pirates but doesn't kill them, Mother Brain orders sentry robots to kill them instead, angering Samus. The manga shows Mother Brain's frustration with the Chozo and with the many raids of the Space Pirates. She also mentions the Metroids as being her and the Chozo's children.

Later on, she takes it upon herself to "dispose" of many of the Chozo, calculating that by taking command of the Space Pirates, she could bring true order to the galaxy. She designated herself, a Chozo named Grey Voice, Ridley, and Samus Aran as Space Pirate commanders, though Samus refused to cooperate.

Mother Brain also stated that she was the one who created Samus's Power Suit.

After it is revealed that Grey Voice has only been pretending to be a Space Pirate commander so that he can get closer to her, he then attacks Mother Brain, claiming that even though he will allow the Pirates to have the planet, he will not allow a "defective" product to continue. However, Grey Voice soon discovers that the Zebetite shield is too strong and that his attacks cannot get through; Mother Brain is then rescued by Ridley, who comes and battles with Grey Voice. As Grey Voice is killed by Ridley's flames, Mother Brain mocks him as a flightless bird.

Later on, it comes to light that Mother Brain is, in fact, using the Pirates to further her own goals and that she is using them to fight the Galactic Federation so that both become weakened. She plans on using an "evolved" form of the Metroid, an intelligent one, so that she may become the ruler of the universe. She seems to refer to all beings, from the Pirates to Ridley to the Federation, as simple beasts.

Captain N: The Game Master

Mother Brain is the main antagonist of the cartoon Captain N: The Game Master. Controlling a converted asteroid called Metroid, she plots to capture the Palace of Power and take over all of Videoland.

Super Smash Bros.

Super Smash Bros. Brawl

Mother Brain appears as a sticker, which increases flinch resistance when equipped by any character.

Super Smash Bros. for Wii U and 3DS

Mother Brain appears as an Assist Trophy and a regular trophy. When summoned, energy rings attack the opponents. While that is going on, Mother Brain grows in size. She then proceeds to shoot a powerful beam out of her eye. She can be defeated by hitting her in the back enough times after the glass of her capsule breaks.

Super Smash Bros. Ultimate

Mother Brain returns as an Assist Trophy, behaving exactly the same as in Super Smash Bros. for Wii U and 3DS. She also appears as a primary shield-type Spirit that can be enhanced at level 99 to her second form from Super Metroid, which allows the player to start each battle giant-sized when equipped. Her Spirit Battle is against Dark Samus, who summons Mother Brain as a hostile Assist Trophy.


Mother Brain resembles a human brain, though she is more spherical in shape. She has short metal spikes protruding from the top of her "head" and a single gigantic eyeball with a red iris. Unlike the Federation's Aurora Units, which are neuron masses enclosed in metallic shells, Mother Brain's hide is strong enough that she remains completely exposed. Several power cables come off the bottom of her body, and she appears to be permanently attached to the floor of her tank, unlike the Federations' Aurora Units, which are free-floating. Her tank, called the Control Capsule in the Super Metroid comic, is made of Zebetite and is protected by multiple gun turrets, Rinka, and more Zebetite barriers which serve as both protection and energy resources.

In Super Metroid, she has a number of changes. She is now an orange color and appears to be more mechanized. Her eye is now white and has no pupil (though Metroid: Other M appears to have retconned this and gave her a more detailed eyeball) and she has a metallic mouth, complete with tongue and spittle, from which she can roar. Her most notable addition, of course, is a new mechanized body, which connects to her immediately following forcible disconnection from her capsule's life-support systems. The body itself stands taller than Ridley and is capable of dozens of attacks, including red energy beams, bombs, blue ring lasers, beam shots via her eye, and her most powerful attack, the Laser Brain Attack. This mechanized body strongly resembles a Torizo, suggesting similar technology.

Leadership Debate

Mother Brain's role in the Metroid series is vague. There is a debate as to whether she or Ridley is the leader of the Space Pirates (this question growing more confused with the addition of High Command from the Metroid Prime games). Her body appears to be based off Torizo technology. According to the manual for Super Metroid and the manual for Metroid: Zero Mission. and the official manga, Ridley is the general of the Space Pirates while Mother Brain is the biological computer which controls Zebes' defenses.

However, in the manuals for Metroid and Metroid Fusion, the box for Metroid: Zero Mission game box, the Super Metroid Nintendo Power comic, and the intro to Super Metroid in-game introduction refer to Mother Brain as the leader of the Space Pirates, with the manual for Metroid. 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. Also, 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.



  • Since the Metroid series was inspired by the Alien franchise, Mother Brain's name may have derived from "Mother", the name of the computer on the Nostromo.
  • listed Mother Brain as #5 on their "Top 10 Female Video Game Villains" list.
  • In Captain N: The Game Master, Mother Brain was voiced by the late Levi Stubbs of The Four Tops, who was best known for voicing Audrey II in Little Shop of Horrors.


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