In the religion of ancient Babylon, Tiamat is a primordial goddess of the sea, mating with Abzû, the god of the groundwater, to produce younger gods. She is the symbol of the chaos of primordial creation.

It is suggested that there are two parts to the Tiamat mythos, the first in which Tiamat is a creator goddess, through a sacred marriage between different waters, peacefully creating the cosmos through successive generations.

In the Enûma Elish, the Babylonian epic of creation, she gives birth to the first generation of deities; her husband, Apsu, correctly assuming they are planning to kill him and usurp his throne, later makes war upon them and is killed.

Enraged, she also wars upon her husband's murderers, taking on the form of a massive sea dragon. She is then slain by Enki's son, the storm-god Marduk, but not before she had brought forth the monsters of the Mesopotamian pantheon, including the first dragons, whose bodies she filled with "poison instead of blood". Marduk then forms the heavens and the Earth from her divided body.