Oceanus, Greek God and husband to Tethys, was a god during the era of Titans. Gaea was his mother, but his father was either Chaos or Uranus, as there are differing stories of his origin.
Oceanus was married to his sister Tethys, and she bore him many children called Oceanids. The Oceanids were lesser gods and goddesses of the rivers and smaller bodies of water. The couple was so fertile that the overproduction of the aqueous elements of nature would cause floods, so they divorced to stop this from happening.
Unlike many of the Titans, such as Atlas, Oceanus did not take part in the rebellion of the Titans against Zeus. Since he did not participate in the rebellion, Zeus allowed him to rule over his kingdom of water.