Chozo

The Chozo are a fictional species of bird-like extra-terrestrials existing within the Metroid video game universe. The Chozo raised Samus Aran and outfitted her with armaments. They are portrayed as mysterious and godlike throughout the Metroid series. The origins and age of the Chozo race and civilization are unknown, but they were once a great race spread across several planets in the Metroid universe, though none have been seen alive in the current time of the games. The Chozo were wise, knowledgeable, and extremely technologically advanced. According to Metroid Prime, the Chozo decided that there was nothing more left to know, and decided to sit back and watch other civilizations grow instead. While the Chozo mostly appeared as a peaceful race, statues depicting "Chozo Warriors" can be seen in Metroid Prime. Chozo have thrived on most major Metroid planets so far, namely Zebes, Tallon IV, SR388, and Elysia. Metroid Prime 2: Echoes notes that they had contact with the Luminoth and several other ancient races, and Metroid Prime 3: Corruption shows that they offered a peaceful alliance with the Reptilicus natives of Bryyo as well.

The use of the word Chozo in reference to the bird-like race is actually the result of a miscommunication between Nintendo Co. Ltd and Nintendo of America. The word chozo (鳥像) is actually Japanese for "bird sculpture", and was used in reference to the sculptures of the bird-like race that hold power ups in the various games. Hence, the localization team incorrectly thought that this word was referring to the race the sculptures were depicting, rather than the actual sculptures themselves. In the Japanese versions of the games, the bird-like race is only ever identified by the generic term chōjin-zoku (鳥人族, lit. "race of bird people").

Zebes (Metroid, Metroid: Zero Mission)
The Chozo on Zebes lived on the surface of the planet, in a rocky area known as Chozodia, though some of their statues can be found underground - it is not known whether these have been moved from Chozodia by the Space Pirates for research. The Chozo brought Samus Aran to Chozodia and let her grow up with them after her family was killed. When Aran became an adult, the Chozo created her trademark Power Suit and she left the planet.

Metroid e-manga
In the official Metroid manga, which chronicles Samus's early life before Metroid/Zero Mission, the Chozo are quite different from the image players get from reading the Metroid Prime Logbook data. Rather than being mysterious, godlike beings, they show more emotion (e.g. They break into a huge argument when Old Bird brings Samus to Zebes). At the moment, the only major Chozo characters are Grandpa Bird (Tori-jisan, "Old Bird" literally, but referred to by Samus as "Grandpa") and his assistant/accomplice, Grey Voice.

The reason for the decline and eventual fall of the Chozo civilization on Zebes has not yet been revealed, however, it is implied that the Space Pirates (and possibly Mother Brain) may have had a hand in their disappearance. In the official Metroid e-manga, the Chozo who raised Samus are alarmed to discover the presence of poisonous flowers on Zebes, flowers which are implied to have been planted by the Space Pirates. Mother Brain at that point was still being used as a kind of planetary control computer by the Chozo, although whether it had any part in their fall has not been revealed. Based on the events in the e-manga, it's safe to assume that the final disappearance of the Chozo is a recent event as they were still quite known within the Federation during that time. Whether or not their civilization was already in decline at that point, or whether their fall was abruptly caused by external factors is unknown.

Tallon IV (Metroid Prime)
The Chozo that colonized Tallon IV were originally from Elysia, as it is stated in the lore the player can read about when they go to SkyTown in Metroid Prime 3: Corruption. Seeking greater wisdom and a state of enlightenment, they decided to abandon their technology and live in complete harmony with nature, crafting temples and buildings out of stone, molding them delicately around giant trees and water springs. After finishing this monumental city of nature, the Chozo eventually found the enlightenment they sought, and transcended beyond their mortal forms, possibly through some sort of deep meditative status. Sometime after this, a giant meteorite impacted the planet, filled with the radioactive substance Phazon (known to the Chozo as "The Great Poison"), which started corrupting Tallon IV's ecosystem. This cataclysmic event somehow ripped the Chozo from whatever dimensional plain they had transcended to back to Tallon IV, turning them into ghosts in the process. In order to save the planet from the spread of Phazon (and themselves from the madness the Phazon caused them), the Chozo constructed a giant temple, which they called the Cradle, above the meteor's impact crater. With the mystical power of twelve Chozo Artifacts, this temple generated a vast barrier that kept the majority of Phazon underneath the planet's surface at bay.

In Metroid Prime 3: Corruption, it is stated in a research data log that there were a number of Chozo on Tallon IV who actually survived the entire incident regarding the Phazon meteor and left the planet to travel to an unknown location. This means that there were Chozo who had not reached an enlightened state of being before the meteor hit, making it highly probable (and much more sensible) that it was this group of Chozo who actually built the physical portions of the Artifact Temple instead of the Chozo Ghosts, who probably had more to do with the creation of the Artifacts themselves.

Both Space Pirates and Samus later find the planet, and discover the Chozo Ruins and the barrier. They discover that the barrier was actually keeping in a powerful creature that lived inside the meteorite, known as Metroid Prime (known to the Chozo as "The Worm"). Note that Metroid Prime actually did escape from the barrier in the NTSC version, but went back to the crater again. The Artifacts are guarded by Chozo Ghosts, explained in the game as Chozo souls corrupted by the Phazon, and called "The Turned" by the other Chozo. Samus eventually manages to find all the artifacts, unlock the barrier, and seemingly destroy Metroid Prime (however if a player manages to achieve a 100% completion, an extra scene after the credits will show Dark Samus' hand emerge from Prime's remains).

SR388 (Metroid II: The Return of Samus)
The Chozo that lived on SR388 discovered the X Parasites that were destroying the natural order, as stated in the Metroid Fusion manual. To stop these parasites, the Chozo artificially created the Metroids as a kind of "natural enemy" to the X. The Fusion manual also mentions that "Metroid" means "ultimate warrior" in the Chozo language. The Chozo later disappeared from this planet as well, only leaving some underground ruins behind.

Elysia (Metroid Prime 3: Corruption)
The constant storms that plagued the planet Elysia's surface kept any sort of civilization from living there, so instead the Chozo created hundreds of floating pods in the skies of Elysia, far above the clouds, yet still within the mildly oxygenated atmosphere. Interconnected by a vast system of electric cables and walkways, this collection of pods became known as SkyTown, and was an observatorial haven for the Chozo in gathering research about the universe. However, frustrated by the city's almost constant need of repair, they created the Elysians, a race of machines that could think independently and self-maintain. The Elysians guarded SkyTown and kept it functioning centuries after the Chozo had left. Unfortunatley, a lack of fuel and mechanical parts forced the Elysians into a deep slumber in order to preserve what little they had. The satellites and observational components of SkyTown fed the information they gathered directly into the Elysians' minds as they slumbered, allowing them to see the horrible fate of their Chozo creators on Tallon IV. When the Federation suddenly arrived in SkyTown, the Elysians were reactivated and prepared to defend themselves and their home. When the Federation announced its peaceful intentions, both sides reached a truce, which eventually resulted in the Treaty of Elysia. The treaty allowed the Federation the use of SkyTown's data collection systems in exchange for fuel and maintainence parts much needed by the Elysians. However, the planet's atmosphere became too much for Federation researchers to handle safely, so they built Aurora Unit 217 into SkyTown's network to replace the humanoids.

Chozo Statues
Chozo Statues are a common feature in Metroid games. They generally depict a sitting Chozo with its hands out in front of it, holding an item for Samus to obtain. Some Chozo statues have other functions, such as opening up hidden passages or regenerating energy in Metroid: Zero Mission. In Super Metroid, Samus encounters several Torizos. They are living Chozo statues that attack Samus once she takes the items from them. Their origin and purpose is unknown.

The Tallon IV ruins of Metroid Prime hold the most complete record of Chozo activity found to date. The Chozo worked hard to perfect their statuary and only the most skilled artisans were allowed to construct them. Some statues have special powers, often helping Samus in the game. One Lore entry says that "Those who respect our statues will know the friendship of the Chozo. Those who deface or destroy them will know our wrath, unfettered and raw." This is proven in the battle with Meta Ridley. During the battle, he smashes the statues that gave Samus information on the Chozo Artifacts. When Samus wins the battle, the nearby Chozo statues turn red and shoot beams from their eyes, hitting Meta Ridley in the chest and knocking him off a cliff to fall to his apparent doom. (his wings were destroyed by Samus during the fight)

In Metroid Fusion a single chozo statue is found in the research station, however it turns out to be a mutated X-parasite mimicking one. Since the X-parasites can only mimic organisms or objects with a large number of organic parts, it can be assumed that the statues may in fact be "alive."

In Metroid Prime 3: Corruption, a pair of Chozo statues are found on the planet Elysia. One is covered with Phazon and must be rid of the substance using the Hyper Ball. The other holds the Spider Ball. Another statue is seen in the icy area of Bryyo. It is much larger than other Chozo Statues, towering hundreds of feet above the ground, and is depicted holding out a hand to a matching Bryyonian statue, offering knowledge and a peaceful alliance. The Screw Attack can be found between the two statues, closer to their waist level.