Oocca

First introduced in Twilight Princess, the Oocca (天空人 Tenkuujin, lit Sky people) are an ancient race of sky beings who live in the City in the Sky, and are the race which Ooccoo belongs to. They have bird-like bodies and oblong heads with humanoid faces. Some Oocca are familiar with the Hylian Language and are capable of speaking it, but they also have their own language which sounds like jabber of strange squawking noises.

History
Despite their small bodies, the Oocca are seen to be highly developed in terms of technology. They have built massive cannons that are capable of launching someone to and from the heavens, crafted a rod that can bring life to inanimate objects, and even built their own city in the sky that is held up by powerful propellers.

Shad, following in his father's footsteps, has devoted his life to studying the Oocca. According to him, the Oocca are the closest race to the gods, closer even than Hylians, whom the Oocca themselves are said to have created. After the sky beings created the Hylians, they simultaneously formed their own city: a city that floats in the heavens which can only be reached via a Sky Cannon.

Strangely, however, the canonical Japanese in-game text confirms that the Oocca in fact did not create the Hylians, (which was in fact a mistranslation by NoA) but Hyrule itself after the three Godesses created the Sacred Realm and the Triforce, and the Oocca did not build the City in the Sky until after the Godesses created the Hylians.

To maintain contact with with the Royal Family of Hyrule, the Oocca created a mysterious rod known as the Dominion Rod. This rod would only be carried by one known as the messenger to the heavens, who would then use the rod whenever the Royal Family needed to communicate with the Oocca. Along with the rod of the heavens, the sky beings left the Ancient Sky Book with the Sheikah, which was to be given by royal decree to the heavenly messenger.

It can be assumed that by the time Twilight Princess takes place, the Oocca have stopped communicating with the Royal Family of Hyrule. Why this happened is unknown.

City in the Sky
When Link visits the City in the Sky, he can use the Oocca he finds walking about to progress through the dungeon by picking them up and using them to float across large gaps, much like he would use a Cucco. Although the Oocca squawk madly when picked up, Midna tells Link that they don't seem to mind, and in fact wish to help him.

Trivia
The Oocca bear a resemblance to the bird-like creatures in M. C. Escher's painting "Another World", upon which many believe the Oocca's appearance may be based. Several of them can be seen walking on the walls inside the dungeon, similar to the creatures.