The Chozo are an ancient race of sentient avian beings from the Metroid series. Highly intelligent with greatly sophisticated science and culture, the Chozo were regarded as one of the galaxy's higher races. Their civilization was widespread; remnants of Chozo architecture and even technology remains on several planets. The Chozo themselves, however, are suspected to be extinct as no living Chozo have appeared in any of the Metroid games.
The Chozo's earliest known history begins with their colonization of the planet Elysia 1500 years before the events of the first Metroid game. There, the Chozo created SkyTown, an airborne city with individual research pods with what appears to be rocket engines under them, allowing them to hover. As the Chozo added on more to SkyTown, they spent great amounts of time for research and studies. This inspired them to create mechanoids to build and perform maintenance to the facility, while the Chozo studied space and its quantities.
400 years after the Elysian debut, the Chozo departed from the planet so that other races may use the SkyTown to learn of their knowledge and the Elysian mechanoids may find answers to the mystery of an unknown planet discovered on the far fringes of the galaxy. The Chozo moved on and began to colonize the planet Tallon IV, where a massive stellar object eventually collided with the planet. This was recorded by the Elysians as they were in stasis 200 years after their creators' departure, caused by the lack of critical supplies, and stored in their memories in "dreams." The Elysians remained in their slumber for 835 years.
The Chozo who settled on Tallon IV chose to build a society that did not depend upon technology, preferring to live in harmony with nature. However, their time on Tallon IV proved to be finite as they foresaw the doom of their adopted world. A Leviathan Seed struck the planet and began to saturate the land and all forms of life with mutagenic Phazon. Powerless to stop the spreading corruption, the Chozo made every attempt to contain the "Great Poison", as they called it. For this purpose they gathered all of their remaining resources and constructed a temple to seal away the source of the Phazon. A lock, requiring twelve artifacts to open, was placed in the temple. The Chozo realized that they could never completely eradicate the Phazon infestation. In their visions they saw the coming a of a saviour and decided to leave behind tools, weapons and armour for the saviour to use in battle with the Phazon. Decades later, Samus Aran fills this prophecy by destroying the source of Phazon on Tallon by utilizing this Chozo technology.
Sometime prior to the colonization of Zebes, several Chozo had established a research facility on the planet SR388. There, they studied the many forms of fauna and flora that the planet had to offer, but also discovered that much of the planet's biosphere was being destroyed by the rampant spread of a parasitic organism simply dubbed "X". The X parasite was capable of absorbing the DNA of its host organism and using it to take on the form of its host after the host's death. Seeing the danger that X posed, the Chozo committed themselves to creating a countermeasure, and so their labours resulted in the birth of a new parasitic organism designed to feed on the X. This organism became known as the Metroid and while it appeared to drive the X parasites to extinction, it eventually multiplied at such a rate that it quickly became the dominant predator on SR388. The Metroids fed not only on the X but on all living things, absorbing their very life energy. Unable to stop the spread of the Metroids, the Chozo were forced to abandon the planet before they all became victims of their own creations.
Many of the Chozo opted to colonize the planet Zebes rather than settle on Tallon IV. Here, they committed themselves to the advancement of science, creating such marvels as the biological computer known as Mother Brain. It was also here that the Chozo raised Samus Aran, a human girl who had formerly resided on the Galactic Federation colony of K-2L until her home was destroyed by Space Pirates. The orphaned Samus learned and grew under the tutelage of the Chozo and was gifted with a suit of advanced power armour which she would use in her profession as a bounty hunter when she came of age.
Sometime following Samus' departure from Zebes, the Space Pirates attempted to invade the planet and were successful. Their success was due to the betrayal of the Chozo's bio-computer Mother Brain, which sabotaged the colony's defences and directed the Pirate forces telepathically. The Chozo colonists were all supposedly wiped out and it is believed that the Chozo race may now be extinct, but there may yet be other Chozo settlements located throughout the galaxy where the Chozo still thrive.
The Chozo culture seems to have mostly been a peaceful one, prizing knowledge in all its forms. The Chozo were explorers in every sense of the word, simultaneously seeking scientific and technological advancement, interstellar exploration, and primal shamanistic wisdom. They had an utmost respect of the natural fauna found in every planet they visited, with one exception. They often shared their knowledge and wisdom with other races that were equally advanced as them, as well as ones that were not as advanced as their own. The balance between technology and spiritualism seems to be another defining trait of the Chozo culture. Many of their structures were built of stone, although it is clear they were capable of using far more complicated materials and building techniques. This is most prevalent in the crafting of their statues, which seem to be present in all Chozo colonies. This art form was considered to be a sacred process, reserved only for those Chozo who had lifetimes of experience in such things.