In the original Metroid game, you generally find power-ups being held by birdlike statues. We later find out that these are representations of the Chozo, a technologically advanced race of bird-people who colonized many different planets.
They also raised the young Samus Aran, injecting her with Chozo blood and giving her a Power Suit that mimicked their own tough skin. Their history has never been fully developed, but we know that they originally created a lot of weapons and armor (such as the ones you can find in the games), but eventually dedicated themselves to peace and to helping other races to develop. It often seems that they basically created everything integral to the series, having bred the Metroid themselves in order to fight off the X Parasites of the planet SR388, which would become the Metroid homeworld. They also built the bio-mechanical Mother Brain of Zebes, who later turned evil and allied herself with the space pirates because…well, that’s what sentient supercomputers ALWAYS do in science fiction stories.
We don’t know what happened to the Chozo as a whole, the only known surviving ones living in hiding. One of them, known only as the Old Bird, makes a few appearances in the games and comics based on them.
What I have to wonder is whether it would be possible to breed Chozo with another group of video game birds, resulting in Chozobos.