Abzu

Apsu (アプス, apusu), Abzu in English subtitle translation, is one of the most ancient gods. He is a Babylonian god in the series that embodies the dark matter in the universe (unlike Erebus who in the series embodies the dark but is not seen as a material that expands mass) and the real enemy in the first season of Saint Seiya Ω. Medea choose Kōga as Apsu's Vessel.

Trivia

 * Abzu was created for Saint Seiya Omega, originally the Primordial God Erebos was considered, however he is potentially set to appear in Saint Seiya Next Dimension hence why Abzu was created in its place.