is a series of nonlinear science fiction action games published by Nintendo, featuring side-scrolling, metroidvania, and first-person shooter elements. The player character and protagonist of the series is Samus Aran, a spacefaring bounty hunter who battles Space Pirates and an extraterrestrial species called the Metroid.
Overview
Key:

= Does Not Appear
A dark grey cell indicates that the character was not in the property or that the character's presence in the property has yet to be announced. A Main indicates a character had a starring role in the property. A Recurring indicates the character appeared in two or more times within the property. A Guest indicates the character appeared once in the property.

Protagonists
Samus Aran
is a bounty hunter and the protagonist of the series. Her homeworld was attacked by the Space Pirates, and her parents were murdered by their leader Ridley when she was young, which led to her being taken in by the Chozo, who saved her life and raised her to become a warrior. She wears a futuristic suit with weaponry and movement in mind, allowing ease of movement while having decent armor and blaster cannons (and other weapons, such as rockets, unlocked early in most games), similar to Mega man. It is also likely the reason Samus is able to survive on other planets. Samus also appears in the Super Smash Bros. series as a playable character.

Chozo
The Chozo are a mysterious, sage-like species that are featured throughout the Metroid series. The origins and age of the Chozo race and civilization are unknown. They were once spread across several planets in the Metroid universe, with their home planet being ZDR. Lore entries in Metroid Prime suggest that the race may have traveled to a higher plane of being as opposed to dying out. The Chozo were extremely advanced in technology, and took pride in their elaborate statuary. They also exchanged knowledge with other species, including the Luminoth of Aether, the Reptilicus of Bryyo, and 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. The Chozo were also responsible for raising Samus, infusing her with their DNA and creating her Power Suit, and for the creation and breeding of Metroids to combat the X Parasites. While in the Japanese versions of the games, the beings are only ever identified by the generic term , a misunderstanding during the localization process led to the mistaken adoption of the descriptor , rendered "Chozo", in the English versions instead. In Super Metroid, some of the Chozo statues would rise up and attack Samus; these bosses are called Torizo, substituting the native Japanese word tori "bird" for the usual, Chinese-derived chō. In the late game of Metroid Prime Chozo ghosts appear and attack Samus. Although originally allies, the Chozo became maddened by the Phazon corruption of their planet, and could no longer distinguish friend from foe. In Metroid Zero Mission, Samus is able to enter the Chozo Ruins.
In Metroid Dread, the social structure of the Chozo is explored, revealing they are split into two tribes: the peaceful Thoha, who left their warrior traditions behind to become scientists, and the Mawkin, who retained a warrior culture. The Thoha initially colonized SR388 and encountered the X parasites, genetically engineering the Metroids to serve as their predators. For this reason, the Metroids are calm in the presence of Thoha genes and hostile towards Mawkin. While the Thoha feared both species, the leader of the Mawkin, Raven Beak, saw potential in the Metroids, and ordered the killing of all but one Thoha (Quiet Robe) so they would not obstruct his plans. However, one Mawkin soldier was infected with an X while returning to ZDR and a pandemic broke out, leaving Raven Beak and Quiet Robe the only known living Chozo when Metroid Dread takes place. Since they are both killed during the game, as of Dread the Chozo are believed to be extinct.
In Metroid Manga, which is a prequel to the game series, two Chozo who had a hand in Samus's origins were introduced: Old Bird and Gray Voice. When Samus lost her family to the Space Pirates, they took her under their wings and raised her to become the galactic savior she is today, and Gray Voice was one of the Chozos who donated his DNA to Samus. Gray Voice later joined the Space Pirates under a cover mission to destroy the renegade Mother Brain.





