The Chozo are a race of highly intelligent, bird-like extraterrestrials. The lore left behind by the Chozo colony on Tallon IV states that the Chozo were unsure of their exact origins. At its peak, their civilization stretched to many planets. The Chozo are responsible for raising Samus Aran, the protagonist of the Metroid series, after the death of her parents and the entire K-2L colony. Their history and fate are an overall mystery, although many mentions and evidence of their existence are present throughout the entire Metroid series. It is unknown whether members of their race still survive, as they have never made a direct appearance in any of the games.
The Chozo Civilization
SkyTown and Elysia
According to Lore entries, the Chozo began the colonization of the planet Elysia and the construction of SkyTown roughly 1500 years before the events of the Metroid series. The Chozo created an area 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.
The First Elysian was given self-awareness by the Chozo and marked Year One of the Elysian race. The Chozo sent Observation Satellites through the regions of space to further study the stars. A Chozo researcher discovered an unknown planet that was extremely far away, even in Chozo measurements. The Planet was revealed to be a living sentient, although the rest of the data was lost before any more could be revealed.
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 Elysians may find answers to the mystery of the unknown planet. The Chozo then began to colonize the Planet Tallon IV, and was there that a massive object collided into 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 Tallon IV Colony
The Chozo who colonized Tallon IV made a conscious choice to eschew a civilization of advanced technology. They chose to live in harmony with nature, guided by the providence of the universe. In Metroid Prime, the Chozo play a significant role in the storyline and gameplay elements of the game. Samus can download translated Chozo Lore left behind by the colony, revealing the history of the Chozo who chose to live on Tallon IV. The lore reveals that the abandoning of technology and close harmony with the nature began to change the Chozo who had settled on Tallon IV:
We know not how the ability has come to us, but recently many Chozo have begun to sense things beyond the realm of ordinary perception. Strange sights and inexplicable sensations flood our minds, filling us with visions of past and future. We take this growing ability to be a sign of our burgeoning harmonization with the infinite; perhaps, finally, the universe's secrets are becoming known to us.
— Chozo Lore
Visions of impending doom were a common theme in the foresights of the chozo, but its form and nature were not revealed to them until a Leviathan made impact on the surface of Tallon IV. With their gifts, the Chozo were able to sense that there was something sentient connected to the phazon delivered by the meteor. Forceless to stop the spreading corruption, the chozo made every attempt to contain the poison.  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 savior and decided to leave behind tools, weapons and armor for the savior to use in battle with the phazon. Centuries later, in Metroid Prime Samus Aran fills this prophecy by destroying the source of Phazon on Tallon by utilizing this Chozo technology.
Encounters with other notable species
The Chozo made contact with other advanced species such as the Bryyonians, the Luminoth, the Ylla and Humans. They exchanged knowledge and technology with each other. Being a race with vast experience with technology the Chozo advised their new allies to find a balance between new technology and the native cultures of the different species. These warnings were not always heeded, which led to the destruction of the Bryyonians by their inner conflicts. The Chozo were also responsible for the creation of the Elysians, a race of self aware mechanoids.
In Other Languages
- "The history of the Chozo stretches back into ancient times, so far into the fog of the past that we know not where our ancestors came from. One thing is clear, however: the Chozo who colonized Tallon IV made a conscious choice to eschew a civilization of advanced technology. They chose to live in harmony with nature, guided by the providence of the universe. As this city grows, we plan to honor them with written tributes, carvings etched in stone to remind us always of their legacy." —Chozo Lore (Metroid Prime)
- "We look different... but inside... we have the same 'heart' you do..." —Metroid (manga), Old Bird, Vol 1 Ch 1 Pg(s) 11
- "The Chozo were watchers, studying the depths of space tirelessly to quench their thirst for knowledge." —Sky Town Data - Creators (Metroid Prime 3: Corruption)
- "Several decades passed for the Chozo here at Elysia. The harsh winds and storms began to take their toll on the station, and upkeep began to take up more and more of their precious time. Seeing a need for assistance, they created us. The First Elysian, built by Chozo hands, stepped out of the mechanicreche 1,450.82 years ago. Crude by our current standards, the First was soon given the greatest gift of all by the Chozo. To better assist the creators, the First was given self-awareness. To all other Elysians, the First shared the Chozo gift. This event marks year One of the Elysian reckoning." —SkyTown Data - Gift (Metroid Prime 3: Corruption)
- "The Chozo were watchers, studying the depths of space tirelessly to quench their thirst for knowledge. From this facility they launched observation satellites, firing them into the heavens toward distant worlds. These satellites returned information that allowed them to analyze the various phenomena occurring across the cosmos. Through this process they were able to satisfy their intellectual appetite, one planet at a time. One day, a Chozo Searcher happened upon a very rare discovery. A once-thought-lost satellite delivered information on a distant world. It was incredibly far away, even by Chozo reckoning. Study of the stellar object revealed that it was, in many ways, a planet - and yet also sentient. Alive. This chance event was brief, and the information being collected was lost before the true identity of the planet was revealed." —SkyTown Data - Discovery (Metroid Prime 3: Corruption)
- "In the year 400 of Elysian reckoning, the time for our Chozo creators to leave had arrived. To us they entrusted the station and its purpose. We were to stand vigil and watch over the station until the time when others seeking knowledge and enlightenment arrived. With their departure came one last request from the Chozo Searcher - to continue exploring the skies for the answers to the mysterious planet. We gave her our word and resumed her tireless search. Day after day we hunted for the answers she desperately sought, but our efforts yielded nothing. We failed." —Sky Town Data - Alone (Metroid Prime 3: Corruption)
- "By the year 600, we of Elysia were low on critical supplies and fuel. We created smaller mechanoids to process fuel from the atmosphere of Elysia, but they proved unable to produce a sufficient supply. Unable to secure the necessary resources to sustain ourselves, we entered a state of hibernation to preserve our remaining stores of energy and parts. While we slumbered, the data collected by the station's equipment was fed to us in dreams." —SkyTown Data - Slumber (Metroid Prime 3: Corruption)
- "Time passed slowly as we suffered through our bad dreams. We endured their visions until finally, in year 1435, our automated defense systems were triggered. A number of aliens, well armed and armored, had penetrated our battle screens and entered Elysia Station. Per protocol, we were revived from stasis to defend our home. As we mustered for battle, the aliens communicated with us and declared themselves to be under the banner of peace. A truce was called, and soon we began negotiations with the Galactic Federation. The Treaty of Elysia began a new era of prosperity for us." —SkyTown Data - Federation (Metroid Prime 3: Corruption)
- "Many long years have passed since we Chozo first took root in this land. The passage of time has always been a source of fascination to us; it is the belief of many Chozo sages that the truths of the universe hide within the tumbling currents of time's flow. Even as we search for answers there, however, we find illumination in other, unexpected places. We know not how the ability has come to us, but recently many Chozo have begun to sense things beyond the realm of ordinary perception. Strange sights and inexplicable sensations flood our minds, filling us with visions of past and future. We take this growing ability to be a sign of our burgeoning harmonization with the infinite; perhaps, finally, the universe's secrets are becoming known to us." —Chozo Lore (Metroid Prime)
- "Unforeseen by sages, a meteor came as if from nowhere, casting a dark shadow of debris over the land with the violence of its impact. Its destructive force spent, the fallen star burned itself out rapidly, and the incident should have faded into memory...but the meteor brought with it corruption. A Great Poison burst forth into the land, a strange energy that clawed at natural life with a ferocity that seemed almost sentient. Bound by our ignorance of this phenomenon, we Chozo could only watch in horror as this dark force slowly began to spread across the surface of Tallon IV." —Chozo Lore (Metroid Prime)
- "As the Great Poison reaches ever further into the planet, we Chozo begin to feel the gnawings of despair - before it is too late, we now make our last stand. We have begun to build a temple to contain this darkness; at its heart we will place a Cipher, a mystical lock powered by twelve Artifacts and filled with as much power as we Chozo can harness. We wonder, though - even when we are done, will it be too late? And will the power of the temple, and the Cipher itself, prove strong enough to hold back the poisonous tide that even now swells within the ground, threatening all life?" —Chozo Lore (Metroid Prime)
- "So many creatures suffer beneath the blight upon the land, and we Chozo are no exception. But for all of our pain, we can at least believe in the promise of the future; unlike the apparitions that have begun to appear, entities that feel neither hope nor solace. We call these doomed souls The Turned - taking ghostly Chozo forms, they know no reason beyond the instinctive urge to protect our lands. They will likely exist in limbo forever. We have come to believe that a time may never come when we can once again open the door and banish the darkness we've contained. Even so, our vigilance will forever remain. We believe that on some far-off day, a savior will come and continue what we have begun. For that savior, we will leave our ancient weapons and armor - the soul who can gather them will be the Entrusted One, the only being who can reverse the evil that grows here." —Chozo Lore (Metroid Prime)
- "The ships of Bryyo sped to the stars, in all directions, bearing the banner of peace. Soon we found stellar brethren in the Chozo, the Luminoth, and the Ylla. Starborne knowledge came to Bryyo, and we gladly sent our wisdom to our new friends in return. The hearts of Bryyo were filled with pride, and they honored the Lords of Science for all the wonders we provided. As the time of New Bryyo came to be, the old ways faded. The cries of joy from those who honored Science covered the angry shouts of those who mourned the old ways, the Primal Traditions." —Bryyonian Data - Age of Science (Metroid Prime 3: Corruption)
- "It is told that the Luminoth were not born of Aether, but of the stars. In the early days, we roamed the greatness of the void, bathing in the glorious light of a thousand stars We met a vast number of enlightened minds... the N'kren, the Ylla, and the Chozo among them. Each of them, we found, had claimed a homeworld and formed a deep bond with it. In time, we decided to do the same." —Luminoth Lore (Metroid Prime 2: Echoes)
- "In time, wonders of Science were not enough for those who held the Primal Traditions in their hearts. The warnings of the Chozo—to seek balance between old and new ways—were not heeded by the Lords of Science, myself included. We forged on, ignorant of the rage in the hearts of the Primals. The time came when Sfimas, First Lord of Science, denounced the Primals and their Traditions in the center of the Royal City. It was flame to a dry forest. The Age of Science ended, and the Age of Schism was born." —Bryyonian Data - Age of Schism (Metroid Prime 3: Corruption)