Chozo

The Chozo are a species of avianoid extraterrestrials. It was the Chozo who raised Samus Aran after Ridley and his Space Pirates attacked her colony home of K-2L, killing everyone there, including her parents. They also later outfitted her with her customized armaments that make her so deadly. They are portrayed as mysterious and godlike throughout the Metroid series. They also appear as statues in the Metroid series and they usually are holding some sort of power-up for Samus Aran to equip.

Information
The Chozo are responsible for creating the original Metroids on the biosphere of the planet SR-388. Also in the manual for Metroid Fusion, it is said that Metroid is Chozo language for "Ultimate Warrior". It is unknown whether or not Metroids were created in an attempt to stop the X Parasites from destroying SR-388's ecosystem, but it was discovered by scientists at the Space Colony Ceres that the Metroid's energy abilities could be used for the good of mankind. Chozo ruins have been discovered on the planets Zebes, Tallon IV, SR388, Elysia, and Bryyo. The Chozo are currently either extinct, critically endangered, transcendent, or in hiding; it is likely a combination of two or more of these that caused the Chozo to disappear.

The Chozo civilization was one of the oldest and most technologically advanced in the Metroid universe. Much of its technology is not fully understood by the galaxy’s current inhabitants. The ruins on Tallon IV are a sort of regression; the Chozo, or perhaps only a few colonists, integrated themselves with the planet's biosphere. They did not entirely abandon their technology, but for the most part the Tallon IV colony was made of simpler material, and the indigenous organisms were allowed to roam freely through the civilization. They viewed the natives with reverence and respect, hoping to become enlightened in their tending of other life. According to the North American version of Metroid Prime, the Chozo of Tallon IV eventually achieved this enlightenment and left their bodies behind, inhabiting another dimensional plane and wandering the universe in contemplation. However, the European version is quite vague about what happened to the Tallon IV Chozo and where they left; with this being said, the Prime series was made in America, and therefore the American version should be considered the canon.

The Tallon IV ruins 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, oftentimes helping Samus. One statue 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 you information on the Chozo Artifacts. When you win the battle, the nearby Chozo statues turn red and shoot beams from their eyes, hitting Meta Ridley in the chest and knocking him off of a cliff.

The decline of the Chozo colony on Tallon IV can be directly attributed to that planet's contamination by Phazon (known to the Chozo as the “Great Poison”). Once Phazon infected Tallon IV, its radiation ripped the Chozo from the dimension they had inhabited and forced them to "walk as ghosts" on Tallon IV. The mortal bodies of the Chozo had presumably withered away while the Chozo were living in another plane of existence. However, they could not return to the dimensional environment they had inhabited, and some of the Chozo spirits were slowly driven insane by the Phazon, becoming Chozo Ghosts (known to the Chozo as The Turned). Samus often encountered them near Chozo worship sites. Unfortunately for Samus, they appeared to refuse to permanently die, and she would have to battle them over and over while moving through areas.

Disappearance
The reason for the decline and eventual fall of the Chozo civilization 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 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, which was quite confusing for all involved, except the strangely pacifist Space Pirate. 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.

Terminology
The Chozo language was a lingua franca once but was wiped out by the Space Pirates. The Chozo runes in Metroid Prime are the keys to their language.

Chozo Lore
On Tallon IV, Samus discovered Chozo Lore inscriptions, which revealed some history of the Phazon and Metroid Prime, and the fate of the Tallon IV Chozo.

Torizo
Torizos look just like standard Chozo statues, but while Chozo statues are usually beneficial to Samus Aran by giving her new equipment and items, a Torizo comes to life and attack.

Three Torizos were known to have existed on Zebes. The first was encountered in Crateria, posing as an ordinary Chozo statue holding the Morph Ball Bombs, but came to life to attack when the bombs were taken. The second Torizo was gold and considerably more powerful than the first, found in the depths of Norfair within Ridley's Lair. While it held no item of its own, defeating it allowed Samus to reach the Screw Attack.

Samus reached a third Torizo inside of the Mother Brain's new lair within the new Tourian. This one, however, turned out to only be a dried-up husk that crumbled when touched. Initially confused at this turn of events, the infamous 6' tall secretly-female bounty hunter discovered that the creature was sucked dry by the baby Metroid she had taken from SR388 and that Ridley stole from the Ceres Space Colony, which had grown to massive proportions. This gave her the impression that the Metroid - who considered Samus as its mother - was saved the trouble of battling this final, presumably most powerful, Torizo.

One of the early bosses on the Biologic Space Laboratory Research Station is an X Parasite mimicking a Torizo.

A Chozo inscription on Tallon IV stated: "Still [other statues] are guardians of our secret ways, and these can be as terrible as they are beautiful." This may indicate that Torizo are not a separate species at all, and are in fact golems, similar to Repticus war machines.