ancient Sumerian hero and king of Uruk (Erech) (Erech), a city-state in southern Mesopotamia, who is thought to have lived at the end of the 4th or beginning of the 3rd millennium BC. Along with Lugalbanda and Gilgamesh, Enmerkar is one of the three most significant figures in the surviving Sumerian epics.

Although scholars once assumed that there was only one epic relating Enmerkar's subjugation of a rival city, Aratta, it is now believed that two separate epics tell this tale. One is called Enmerkar and the Lord of Aratta. The longest Sumerian epic yet discovered, it is the source of important information about the history and culture of the Sumero-Iranian border area. According to this legend, Enmerkar, son of the sun god Utu (Shamash), was envious of Aratta's wealth of metal and stone, which he needed in order to build various shrines, especially a temple for the god Enki in Eridu. Enmerkar therefore requested his sister, the goddess Inanna (Ishtar), to aid him in acquiring material and manpower from Aratta; she agreed and advised him to send a threatening message to the lord of Aratta. The lord of Aratta, however, demanded that Enmerkar first deliver large amounts of grain to him. Though Enmerkar complied, the lord of Aratta refused to complete his part of the agreement; threatening messages were again sent out by both men, each claiming the aid and sanction of the goddess Inanna. The text becomes fragmented at that point in the narrative, but in the end Enmerkar was apparently victorious.

The other epic relating the defeat of Aratta is known as Enmerkar and Ensuhkeshdanna. In this tale the ruler of Aratta, Ensuhkeshdanna (or Ensukushsiranna), demanded that Enmerkar become his vassal. Enmerkar refused and, declaring himself the favourite of the gods, commanded Ensuhkeshdanna to submit to him. Although the members of Ensuhkeshdanna's council advised him to comply with Enmerkar, he listened instead to a local priest, who promised to make Uruk subject to Aratta. When the priest arrived in Uruk, however, he was outwitted and killed by a wise old woman, Sagburru, and the two sons of the goddess Nidaba. After he learned the fate of his priest, Ensuhkeshdanna's will was broken and he yielded to Enmerkar's demands.

A third epic, Lugalbanda and Enmerkar, tells of the heroic journey to Aratta made by Lugalbanda in the service of Enmerkar. According to the epic, Uruk was under attack by Semitic nomads. In order to save his domain, Enmerkar required the aid of Inanna, who was in Aratta. Enmerkar requested volunteers to go to Inanna, but only Lugalbanda would agree to undertake the dangerous mission. The epic concerns the events of Lugalbanda's journey and the message given him from Inanna for Enmerkar. Although obscure, Inanna's reply seems to indicate that Enmerkar was to make special water vessels and was also to catch strange fish from a certain river.