Tiamat

In Babylonian mythology, Tiamat is the goddess who personifies the sea - not the sea as it is now known, but the sea before there was anything else. She is primordial chaos itself, monstrous and vast, sometimes imagined as a serpent or a dragon, though no image of her survives from the earliest sources. In the Enûma Elish, the Babylonian epic of creation, Tiamat gives birth to the first generation of gods. But the children she brings into being grow restless and unruly, and in time they turn against her. She rises to make war on her own offspring, and is killed by the storm-god Marduk. From her body, split in two, he forms the heavens above and the earth below. Everything that exists comes from what was undone.