Wind Fish

The Wind Fish (かぜのさかな, Kaze no Sakana) is a large, flying whale who makes his home atop Tamaranch Mountain on Koholint Island, inside of a giant egg. He starred in Link's Awakening.

The Wind Fish is a deity of sorts that is the creator of Koholint Island. During the course of Link's Awakening it is revealed that Koholint Island is a dream of the Wind Fish, and that, should the Wind Fish wake, the island and all its inhabitants would vanish. This presents a moral dilemma for Link, as to finish the game, Koholint and all of the characters living on it must disappear. This is unavoidable upon beating the game, however, as Link only learns the true nature of the Wind Fish until after the final Nightmare has been defeated.

The Ballad of the Wind Fish is recreated during a minigame in Majora's Mask, but only in name since it sounds nothing like this version.

Theories
It is possible that the Windfish is actually Lord Jabu-Jabu. Both are said to have godlike powers, and they share visual similarities as well. In Ocarina of Time, Jabu-Jabu can be seen in Zora's Domain, but when Link returns seven years later, Zora's Domain has frozen over and Jabu-Jabu has disappeared. If Jabu-Jabu is actually the Windfish, he would have flown out of Zora's Domain before it was frozen over.

There is another theory that the Wind Fish is the Ocean King, as both Koholint and the Great Sea in the Phantom Hourglass were only a "dream" of LA Link, and WW Link (as well as Tetra) As well, the Ocean King was willing to grant a wish to Linebeck for his help, Marin had wished to the Wind Fish to be a seagull, in both instances (assuming you did not die once in LA) the wishes are granted.