Utu later worshipped by East Semitic peoples as Shamash, was the ancient Mesopotamian god of the sun, justice, morality, and truth, and the twin brother of the goddess Inanna, the Queen of Heaven. His main temples were in the cities of Sippar and Larsa. He was believed to ride through the heavens in his sun chariot and see all things that happened in the day. He was the enforcer of divine justice and was thought to aid those in distress. According to Sumerian mythology, he helped protect Dumuzid when the galla demons tried to drag him to the Underworld and he appeared to the hero Ziusudra after the Great Flood. In the Epic of Gilgamesh, he helps Gilgamesh defeat the ogre Humbaba.
Utu was the twin brother of Inanna, the Queen of Heaven, whose domain encompassed a broad variety of different powers. In Sumerian texts, Inanna and Utu are shown as extremely close; in fact, their relationship frequently borders on incestuous. Utu is usually the son of Nanna, the god of the moon, and his wife, Ningal, but is sometimes also described as the son of An or Enlil. His wife was the goddess Sherida.
Utu was worshipped in Sumer from the very earliest times. His main temples, which were both known as E-babbar (“White House”), were located in Sippar and in Larsa.
In Sumerian texts, Utu is described as “bearded” and “long-armed”. He was believed to emerge from the doors of Heaven every day at dawn and ride across the sky in his chariot before returning to the “interior of heaven” through a set of doors in the far west every evening. Utu’s charioteer was named Bunene. Cylinder seals often show two gods holding the doors open for him as he wields his weapon, the pruning-saw, a double-edged arch-shaped saw with large, jagged teeth, representing his role as the god of justice.
The Sumerians believed that, as he rode through heaven, Utu saw everything that happened in the world. Alongside his sister Inanna, Utu was the enforcer of divine justice. Utu was believed to take an active role in human affairs, and was thought to aid those in distress. In the Sumerian poem The Dream of Dumuzid, Utu intervenes to rescue Inanna’s husband Dumuzid from the galla demons who are hunting him. In the Sumerian flood myth, Utu emerges after the flood waters begin to subside, causing Ziusudra, the hero of the story, to throw open a window on his boat and fall down prostrate before him. Ziusudra sacrifices a sheep and an ox to Utu for delivering him to salvation.
In the Sumerian King List, one of the early kings of Uruk is described as “the son of Utu” and Utu seems to have served as a special protector to several of that city’s later kings. In the Babylonian Epic of Gilgamesh, Shamash helps Gilgamesh defeat Humbaba, the fearsome ogre who guards the Cedar Forest. Jeffrey H. Tigay suggests that Lugalbanda’s association with the sun-god in the Old Babylonian version of the epic strengthened “the impression that at one point in the history of the tradition the sun-god was also invoked as an ancestor”.