Oceanus

Oceanus was believed to be the world-ocean, or river encircling the world in Greek mythology. He was the Titan God of the Seas, rivers and water, and a child of Oranos and Gaia. His sister was Tethys, and together they created the Potamoi and Oceanids, gods of rivers, streams and springs.

In other tales, Oceanus was portrayed as the 'origin of everything.' He was said to be a river-god whose broad, mighty stream repeatedly flowed in on itself.

During the deposition of his father, Oceanus chose not to side with his five younger brothers. Similarly, Oceanus and the Titanesses remained neutral during the Titanomachy, and when the Titans were defeated, Zeus allowed Oceanus to remain with his task of supplying the rivers and streams. In some tales, he was the son of Nyx.

Oceanus is not in many myths except in the Iliad where he is addressed in a prayer.

Family
Oceanus was the father of many river deities. His sons were the Potamoi, or river gods and his daughters, the Oceanids, nymphs of the seas.

In Fiction
In Rick Riordan's The Last Olympian, the second Titanomachy takes place and Oceanus has an undersea battle with Poseidon, Olympian of the seas. When the other Titans lose their part of the war, Oceanus backs off from Poseidon.