Iddin-Dagan, fl. c. 1910 BC — c. 1890 BC by the short chronology or c. 1975 BC — c. 1954 BC by the middle chronology) was the 3rd king of the dynasty of Isin. Iddin-Dagan was preceded by his father Shu-Ilishu. Išme-Dagān then succeeded Iddin-Dagan. Iddin-Dagan reigned for 21 years He is best known for his participation in the sacred marriage rite and the sexually-explicit hymn that described it.

Dagon or Dagan was a god worshipped in ancient Syria across the middle of the Euphrates, with primary temples located in Tuttul and Terqa, though many attestations of his cult come from cities such as Mari and Emar as well. In settlements situated in the upper Euphrates area he was regarded as the "father of gods" similar to Mesopotamian Enlil or Hurrian Kumarbi, as well as a lord of the land, a god of prosperity, and a source of royal legitimacy. A large number of theophoric names, both masculine and feminine, attests that he was a popular deity. He was also worshiped further east, in Mesopotamia, where many rulers regarded him as the god capable of granting them kingship over the western areas.