An

Anu or An is the divine personification of the sky, supreme god, and ancestor of all the deities in ancient Mesopotamian religion. Anu was believed to be the supreme source of all authority, for the other gods and for all mortal rulers, and he is described in one text as the one "who contains the entire universe". He is identified with the north ecliptic pole centered in the constellation Draco and, along with his sons Enlil and Enki, constitutes the highest divine triad personifying the three bands of constellations of the vault of the sky. By the time of the earliest written records, Anu was rarely worshipped, and veneration was instead devoted to his son Enlil, but, throughout Mesopotamian history, the highest deity in the pantheon was always said to possess the anûtu, meaning "Heavenly power". Anu's primary role in myths is as the ancestor of the Anunnaki, the major deities of Sumerian religion. His primary cult center was the Eanna temple in the city of Uruk, but, by the Akkadian Period ( c. 2334–2154 BCE), his authority in Uruk had largely been ceded to the goddess Inanna, the Queen of Heaven.

Anu's consort in the earliest Sumerian texts is the goddess Uraš, but she is later the goddess Ki and, in Akkadian texts, the goddess Antu, whose name is a feminine form of Anu. Anu briefly appears in the Akkadian Epic of Gilgamesh, in which his daughter Ishtar (the East Semitic equivalent to Inanna) persuades him to give her the Bull of Heaven so that she may send it to attack Gilgamesh. The incident results in the death of Enkidu. In another legend, Anu summons the mortal hero Adapa before him for breaking the wing of the south wind. Anu orders for Adapa to be given the food and water of immortality, which Adapa refuses, having been warned beforehand by Enki that Anu will offer him the food and water of death. In ancient Hittite religion, Anu is a former ruler of the gods, who was overthrown by his son Kumarbi, who bit off his father's genitals and gave birth to the storm god Teshub. Teshub overthrew Kumarbi, avenged Anu's mutilation, and became the new king of the gods. This story was the later basis for the castration of Ouranos in Hesiod's Theogony.