Metroid (Japanese: メトロイド Hepburn: Metoroido) is a science fiction action-adventure video game series created by Nintendo. The series is primarily produced by the company's first-party developers Nintendo R&D1 and Retro Studios, although some installments were handled by other developers, including Fuse Games, Team Ninja, Next Level Games, and MercurySteam.

The series chronicles the missions of space-faring bounty hunter Samus Aran, who protects the galaxy from the depredations of the Space Pirates and their attempts to harness the power of the eponymous Metroids. Metroid combines the platforming of Super Mario Bros. and the exploration aspect of The Legend of Zelda with a decidedly darker atmosphere and a greater emphasis on nonlinear gameplay.

The series consists of twelve games that were released on almost every Nintendo video game console. It is one of Nintendo's most successful franchises, and the games have received varying levels of critical acclaim. As of September 2012, the Metroid series sold over 17.44 million copies.^[1] The series has been represented in other Nintendo media, including the Super Smash Bros. series. Additional media for the Metroid series has also been released, including soundtracks, comic books and manga adaptations.