The Ocean King is the mythical guardian of the World of the Ocean King and is featured in Phantom Hourglass. The evil Bellum invaded the Temple of the Ocean King, sucking the Life Force out of anyone who dared cross its path. Bellum was after the Ocean King's Life Force, but the Ocean King quickly and luckily cloned himself before that could occur. This powerful Deity manages to discretely disguise himself as an elderly man. He hides as a Hylian, going under the name of Oshus, currently residing near the shores of Mercay Island.
In his Hylian form, the Ocean King is the one who informs Link about the Ghost Ship. He tells him that if he wishes to depart for said ship to save Tetra, he must realize that he won't be able to return. As Link acknowledges this, Oshus allows him to take his sword and guides him to the Temple of the Ocean King. There, he introduces and gives the Phantom Hourglass filled with Sand of Hours to the young hero.
As the game progresses, he later reveals Ciela's true identity as the Spirit of Courage. While on the Ghost Ship preparing for the final encounter against Bellum, the Ocean King finally reveals his own true identity. Utilizing the power of the Sand of Hours following the defeat of Bellum, the Ocean King is able to unravel his true and massive form. Before fading away, he speaks with Link and Tetra, telling them that their world will be free from Bellum and its evils.