Characters in the Metroid series

This is a list of notable fictional characters in Metroid, a series of video games developed by Nintendo.

Samus Aran
Samus Aran (サムス・アラン) is the bounty hunter protagonist of the series.

Chozo
The Chozo are a mysterious and sage-like species featured throughout the Metroid series. The origins and age of the Chozo race and civilization are unknown, but they were once spread across several planets in the Metroid universe. Lore entries in Metroid Prime suggest that the race may have traveled to a higher plane of existence as opposed to dying out. The Chozo were extremely technologically advanced, but took pride in their elaborate statuary. They also exchanged knowledge with other species, including the Luminoth of Aether, the Reptilicus of Bryyo, the Elysians of Elysia (robots which the Chozo themselves built). Lore found in Metroid Prime 3 specifically mentions a fellowship of enlightened species that once existed between the Chozo, the Luminoth, the Reptilicus, and another race called the Ylla. While the former three have been expounded on in the series, the Ylla are only mentioned in this piece of lore and have yet to be seen. They were also responsible for breeding the Metroids. In the Japanese versions of the games, the Chozo are only ever identified by the generic term chōjin-zoku (鳥人族), of which the name "Chozo" is an anglicized version. In Super Metroid, some of the Chozo statues would rise up and attack Samus; these bosses are called Torizos. In Metroid Prime, in later areas in game play, Chozo ghosts appear and attack Samus. Although originally allies, they have been maddened by the Phazon corruption of their planet, and can no longer distinguish friend from foe.

Galactic Federation
The Galactic Federation (銀河連邦) is the governing body of the galaxy formed by an alliance of alien species, often contracts Samus with difficult missions to complete, with the aim of eradicating the Space Pirates. Samus trained in the Federation's military before becoming a bounty hunter, leaving some time after a disagreement with her commanding officer, Adam Malkovich. The Galactic Federation's troopers also use powered armor, and their technology usually bears multiple versions of their symbol, a stylized cross-shape. Troopers are also given a basic repeating assault weapon, and in Metroid Prime 3, some are equipped with the Phazon Enhancement Device.

Kraid
Kraid (クレイド) is a gigantic dinosaur-like beast and a member of the Space Pirate's High Command. His most prominent feature is his grotesquely oversized belly. First appearing in the original Metroid, he is the first part of the mini-boss duo along with Ridley. In Super Metroid he appears in his giant form, two screens tall and almost a screen wide. Metroid: Zero Mission retconned his size and appearance, showing he did not grow between games. He was also slated to appear in Metroid Prime as a boss in the Phazon Mines, with a metal dome covering his head and blue Phazon veins on his belly, but was removed due to time constraints. Kraid also makes a guest appearance in the background of the Brinstar Depths stage in Super Smash Bros. Melee.

Metroids
The eponymous in-game Metroids (メトロイド) are large jellyfish-like creatures with quadripartite nuclei. They are capable of siphoning an undetectable life energy from any life form, generally causing the death of the victim in the process. This energy can also be siphoned from the Metroid in turn, allowing it to be used as a living power source. The original Metroid establishes that exposure to beta rays would cause them to multiply very quickly. Metroid II: Return of Samus established a five-stage life cycle in which those Metroids native to SR-388 go through two stages of ecdysis followed by two stages of mutation, thus maturing through five previously unknown forms: Alpha, Gamma, Zeta, Omega, and Queen. Metroid Prime introduced three new, Phazon-mutated forms: Hunter Metroids, Fission Metroids, and Metroid Prime itself. Metroid Prime 2: Echoes has a Phazon-mutated strain of Metroid, the Tallon Metroid. Instead of siphoning all of their power from victims, they can feed directly off Phazon. They are born as Infant Metroids from cocoons and mature into adulthood when exposed to Phazon. The game also introduces Dark Tallon Metroids, Tallon Metroids corrupted by the Ing. In Metroid Prime 3: Corruption, three new mutations of Metroid appear: Phazon Metroid, which is almost exactly like a common Metroid, except that it is capable of phasing in and out of local timespace; Hopping Metroid, which cannot hover, phase out of local timespace, or drain energy, but can fight using its claws as melee weapons and armor for defense; and the Metroid Hatcher, a boss which can float and spawn Phazon Metroids, but cannot phase out of local timespace. Though Metroids are dangerous animals, they are presumably not intrinsically sinister or evil, but act only on instinct. At the end of the second game in the series, Samus spares a baby Metroid, which adopts her as its parent. This Metroid later reappears in the sequel, and in saving Samus's life is killed by Mother Brain. In Metroid Fusion, Samus is injected with DNA from the infant Metroid in order to save her from being killed by the X (giving her the ability to freely absorb X, but also their suceptibility to extreme cold). It is also revealed that the Galactic Federation was breeding Metroids in the Restricted Laboratory in B.S.L. (most of these were killed by one of the SA-X, resulting in the lab's ejection and destruction). An Omega Metroid appears as the final boss (having escaped the Restricted Lab), during B.S.L.'s collision course with SR388. In Super Smash Bros. Brawl, a Metroid appears as a character that can be summoned through an Assist Trophy. Like in the Metroid games, it will attack by attaching itself to a character's head and sucking his/her life.

Metroid Prime
Metroid Prime is the primary antagonist of the Prime subseries. It is a strange creature with the ability to control and horribly mutate anything it attaches to which appears in Metroid Prime as the final boss, and after its defeat, reforms itself as Dark Samus, a doppelgänger of Samus, by stealing her "Phazon Suit". Metroid Prime appeared in Tallon IV shortly after the impact of the Leviathan, a Phazon meteor, and fused with a Metroid unfortunate enough to cross its path. It caused severe damage to the Chozo colony before the Artifact Temple was built to contain Metroid Prime inside the impact crater of the Leviathan. According to the NTSC version of Metroid Prime, Space Pirate miners eventually discovered the creature, eventually dubbing him "Metroid Prime", and after containing him with security units and drones brought to their laboratories to perform experiments. Metroid Prime eventually broke free, and managed to assimilate several weapons and defense systems from fallen security units before going back to the impact crater (the PAL version denies this, with the Pirate Logs only stating the Pirates picked up life signals coming from within the Artifact Temple). After Samus gets all artifacts, she is able to enter the impact crater and fight Metroid Prime. After its defeat, the creature takes Samus' Phazon Suit to reconstruct itself into a body similar to Samus, the being called "Dark Samus". In Metroid Prime 2: Echoes, Dark Samus arrives in Aether chasing the planet's Phazon. Shortly later Samus arrives, and encounters Dark Samus many times, eventually defeating her as Dark Aether was destroyed - but a post-credits scene shows Dark Samus reforming herself in deep space. Metroid Prime 3: Corruption shows a team of Space Pirates returned to Aether to pick up Phazon, and eventually found Dark Samus, who killed a third of the Pirates and brainwashed the rest to be their leader. After discovering Phaaze, Dark Samus begins her mission to spread Phazon across the universe - one of the planets hit was the Pirate Homeworld, in order to turn the rest of the Space Pirates into followers of Dark Samus. In an attack to the Galactic Federation vessel G.F.S. Valhalla, Dark Samus steals a supercomputer, the Aurora Unit, and corrupts Samus and other bounty hunters with Phazon. After Samus destroys the Leviathans of four planets, she goes to Phaaze, where she finally defeats Dark Samus, who then merges itself with the Aurora Unit in a last-ditch effort to defeat Samus. After the Aurora Unit is destroyed, Phaaze explodes, and all Phazon in the galaxy is rendered inert.

IGN listed Dark Samus as the 88th best video game villain.

Mother Brain
Mother Brain (マザーブレイン) is a recurring game boss in the series. Its exact status has always been unclear, as it has been referred to as the general of the Space Pirates, a supercomputer that operates the Space Pirate-occupied world of Zebes, or a councillor of the Chozo. Mother Brain is depicted as a very large brain with cybernetic spikes and a single eye; usually contained in a glass tube which Samus must break to attack it, Mother Brain also rises from the floor with a grotesque body in Super Metroid. Samus seemingly destroys Mother Brain in the original Metroid, but again confronts it in Super Metroid; in this game, Samus is almost defeated, but the baby Metroid intervenes, and Samus once again defeats Mother Brain. It was revealed in Metroid Prime 3 that the Galactic Federation had constructed biomechanical supercomputers called Auroras, and that there were plans for a "Future Aurora Complex", which appears to be the Mother Brain as depicted in Super Metroid. In the trailer for Metroid: Other M, the scene of Mother Brain destroying the baby Metroid is reenacted in an FMV cutscene.

Ridley
Ridley (リドリー) is a recurring antagonist of Samus Aran, a dragon-like extraterrestrial that despite being killed multiple times by her, is always revived by the Space Pirates using cloning or robotics. Other than Samus and the titular Metroids, Ridley is the only character that has appeared consistently throughout most of the games in the Metroid series (the exceptions being Metroid II for the Game Boy, Metroid Prime 2: Echoes for the GameCube, and Metroid Prime Hunters for the Nintendo DS).

Space Pirates
A hostile group known as Space Pirates (スペースパイレーツ) serve as the antagonists of the Metroid series. They are a group of "interstellar nomads" resembling humanoid insects or crustaceans, who plunder colonies and ships. A single Pirate may have many biological differences between individuals of their own species, most likely because of their willingness to perform self-experimentation and mutation. Important leaders include Ridley, the Space Pirate commander, Mother Brain, the biomechanical defense of Zebes controlled by the Space Pirates, and Kraid, a recurring boss. The organization also includes a winged, mantis-like species, the Ki Hunters. The Space Pirates are interested in Metroid research, especially in using Metroids for energy generation, as soldiers, and for experimentation – their Phazon experiments produced all the Metroid variants seen in the Prime games with the exception of Metroid Prime itself.