Oshus

Oshus is an old man on Mercay Island, which Link wakes up on in Phantom Hourglass. He provides Link with a Oshus' Sword.

Later in the game, he fuses Ciela and the fairy found in the Temple of Courage to make one fairy, as Ciela was actually the Spirit of Courage.

Later still, he is revealed to be Sea King Umiou.