|Ancient Mesopotamian religion|
In Sumerian mythology the utukku were a type of spirit or demon that could be either benevolent or evil. The evil utukku were called Edimmu or Ekimmu; the good utukku were called shedu. Two of the best known of the evil utukku were Asag (slain by Ninurta) and Alû. In Akkadian mythology they were referred to as utukki, and were seven evil demons who were the offspring of Anu and Antu.
The proper Sumerian form of the name is UDUG; Utukku is the Akkadian form. It is common to change /D/ to /t/ and /G/ to /k/ in converting Sumerian into Akkadian. The final /-u/ is the Akkadian nominative case-ending.
They were siblings of the Anunnaki. They were in the service of the underworld, and were required to fetch home the fruit of the sacrifices and burnt offerings, which generally consisted of the blood, liver, and other "sweetmeats" of the sacrificed animal.
Utukku appear in Dungeons & Dragons in "Creature Catalog", Dragon #89 (September 1984). It is an outsider from Tartarus that looks like a lion-like humanoid with a quilled mane and a scaly body. They sometimes come to the Prime Material Plane to spread misery and evil and to gather treasure.
Utukku makes an appearance in the video game Final Fantasy XI as a ghost/wraith-class monster.
There are Utukku in the Bartimaeus Trilogy by Jonathan Stroud, acting as prison guards in the British Tower of London. They are portrayed as a type of djinn, and are depicted as especially dim-witted despite their strength, both of which are at odds with the typical mainstream depiction of these entities.
The American black metal band Absu has a track on their self-titled album entitled "Ye Utukku spells". The lyrics contain references to Sumerian deities and mythology, including the Utukku.