Oshus

This man might not look like much, but he was once a powerful deity.

Oshus is the name of the old man who lives on Mercay Island in Phantom Hourglass. Oshus is Ciela's guardian, and she calls him Grandpa. He is also called "old man" by Linebeck. He provides Link with his sword and the legendary Phantom Sword. Whenever he gets angry, he pounds his fish-shaped cane.

Spoiler Warning: This section contains details regarding plot development.

Oshus is actually the Ocean King in disguise. When Bellum attacked him he managed to escape after much of his life force was stolen and make a home on Mercay Island. He is also the one that reveals Ciela's identity as the Spirit of Courage.

Spoiler Warning: Spoilers end here.