Mother Brain (Japanese: マザーブレイン, Hepburn: Mazā Burein) is a fictional character created by Nintendo for the Metroid series.

Mother Brain has made several appearances in other media, most notably as the primary antagonist in Captain N: The Game Master and archenemy of Kevin Keene.

When designing the bipedal version of Mother Brain for Super Metroid, Toru Osawa described what he wanted her to look like as being an "old lady living in my apartment complex".

[3][4] A reimagining of the character also appears in Captain N: The Game Master and its related comic book media, where she serves as the series' primary antagonist and is voiced by Levi Stubbs.

[5] Since her appearance in the original Metroid, Mother Brain has received mostly positive reception, considered a top video game villain by IGN and Guinness World Records Gamer's Edition.

[6][7] In particular, the boss fight against her in Super Metroid has been well-received, with 1UP.com staff finding it one of the most emotionally moving battles in video games and GameSpy writer Ryan Scott calling it "jaw-dropping".