Apsu, Mesopotamian (Babylonian-Akkadian) was god of primeval waters; derived from Sumerian Abzu. As described in the Babylonian creation epic, Enuma Elis, Apsu is killed while sleeping with Enki, who establishes his abode above the deeps. Apsu's death starts the forces in the cosmic war between Marduk and Tiamat. A.G.H.
Jordan, Michael, Encyclopedia of Gods, New York, Facts On File, Inc. 1993, p. 22