Ashur (also, Assur, Aššur; written A-šur, also Aš-šùr) is an East Semitic god, and the head of the Assyrian pantheon in Mesopotamian religion, worshipped mainly in the northern half of Mesopotamia, and parts of north-east Syria and south east Asia Minor which constituted old Assyria. He may have had a solar iconography.
Aššur was a deified form of the city of Assur (pronounced Ashur), which dates from the mid 3rd millennium BC and was the capital of the Old Assyrian kingdom. As such, Ashur did not originally have a family, but as the cult came under southern Mesopotamian influence, he later came to be regarded as the Assyrian equivalent of Enlil, the chief god of Nippur, which was the most important god of the southern pantheon from the early 3rd millennium BC until Hammurabi founded an empire based in Babylon in the mid-18th century BC, after which Marduk replaced Enlil as the chief god in the south. In the north, Ashur absorbed Enlil's wife Ninlil (as the Assyrian goddess Mullissu) and his sons Ninurta and Zababa—this process began around the 14th century BC and continued down to the 7th century.
During the various periods of Assyrian conquest, such as the Assyrian Empire of Shamshi-Adad I (1813–1750 BC), Middle Assyrian Empire (1391–1056 BC) and Neo-Assyrian Empire (911–605 BC), Assyrian imperial propaganda proclaimed the supremacy of Ashur declared that the conquered peoples had been abandoned by their gods.
When Assyria conquered Babylon in the Sargonid period (8th–7th centuries BC), Assyrian scribes began to write the name of Ashur with the cuneiform signs "AN.SHAR", literally "whole heaven" in Akkadian, the language of Assyria and Babylonia. The intention seems to have been to put Ashur at the head of the Babylonian pantheon, where Anshar and his counterpart Kishar ("whole earth") preceded even Enlil and Ninlil. Thus in the Sargonid version of the Enuma Elish, the Babylonian national creation myth, Marduk, the chief god of Babylon, does not appear, and instead it is Ashur, as Anshar, who slays Tiamat the chaos-monster and creates the world of humankind.