Tiamat

Primordial Sea Dragon of Mesopotamian Myth

Tiamat is the oldest dragon deity in human mythology, appearing in the 18th-century BCE Babylonian creation epic Enūma Eliš as the personification of primordial chaos and salt waters. With her consort Apsu (fresh waters), she existed before the cosmos and was mother to all gods. Enraged by the noise of younger gods, she led an army of eleven monstrous creatures into war against them. The storm-god Marduk slew her, splitting her body to form heaven and earth, with her tears becoming the Tigris and Euphrates rivers. In modern D&D, she is reinterpreted as the five-headed (red/white/black/blue/green) mother of the chromatic evil dragons.