The udug (Sumerian: 𒌜), later known in Akkadian as the utukku, were an ambiguous class of demons from ancient Mesopotamian mythology. They were different from the dingir (Anu-nna-Ki and Igigi) and they were generally malicious, even if a member of demons (Pazuzu) was willing to clash both with other demons and with the gods, even if he is described as a presence hostile to humans. The word is generally ambiguous and is sometimes used to refer to demons as a whole rather than a specific kind of demon. No visual representations of the udug have yet been identified, but descriptions of it ascribe to it features often given to other ancient Mesopotamian demons: a dark shadow, absence of light surrounding it, poison, and a deafening voice. The surviving ancient Mesopotamian texts giving instructions for exorcizing the evil udug are known as the Udug Hul texts. These texts emphasize the evil udug's role in causing disease and the exorcist's role in curing the disease.