Mother Brain

The monstrous brain controlling the Space Pirates from within a jar.

Mother Brain is a fictional character created by Nintendo for the Metroid series and serves as one of its most prominent antagonists. Originally designed with a milder appearance resembling an "old lady living in an apartment complex" by Hiroji Kiyotake, her final form was altered by Tomomi Yamane to feature a more monstrous look with dripping saliva and foul breath. She typically appears as a large brain seated within a jar or glass tube, from which she controls the Space Pirates on the planet Zebes. In the original Metroid (1986), she lacks a single large eye; that design debuted in Super Metroid (1994). Mother Brain is best known for being killed multiple times by the series protagonist, Samus Aran.

Quick Facts

Series: Metroid
First: Metroid (1986)
Species: Cybernetic supercomputer (instilled with human DNA)
Creator: Gunpei Yokoi
Designer: Yoshio Sakamoto
Voice: Levi Stubbs (Captain N: The Game Master)

Lore & Background

Mother Brain takes the form of a massive brain situated in a glass tube, often featuring cybernetic spikes. While her standard depiction involves being contained, the Super NES version of Super Metroid reveals a separate mechanical body she controls, not a bipedal form of Mother Brain herself. Hiroji Kiyotake's initial concept for this design was an "old lady living in my apartment complex," but Tomomi Yamane expanded upon it to create a filthy appearance with dripping saliva and foul breath.

In the original Metroid, she utilizes the Metroid species as weapons before being defeated by Samus. She is subsequently rebuilt for Super Metroid, where she reveals a new, much larger form at the end of the game that nearly kills Samus. The Galactic Federation later constructed biomechanical supercomputers called Aurora Units, which are explicitly stated to be based on Mother Brain's technology—not directly stated to be Mother Brain herself. Additionally, an android named MB in Metroid: Other M is partially constructed from her DNA.

Reader's Guide

To defeat Mother Brain, players must first break the glass tube containing her to access the brain itself, though she assumes a bipedal form in Super Metroid. Since Super Metroid (1994), she is characterized by having a single large eye. Her final encounter in Super Metroid involves a massive new form that requires Samus to utilize energy drained from a sacrificed Metroid to survive and win. In Captain N: The Game Master, she acts as the primary antagonist. Mother Brain also functions as a summonable helper character known as an "Assist Trophy" in both Super Smash Bros. for Nintendo 3DS and Wii U and Super Smash Bros. Ultimate. Her design evolution from Osawa's human-like concept to Yamane's monstrous version is a key aspect of her visual history.