Ashnan or Ezina (^dše.tir; both possible readings are used interchangeably) was a Mesopotamian goddess considered to be the personification of grain. She could also be called Ezina-Kusu, which led to the proposal that the goddess Kusu was initially her epithet which only developed into a distinct figure later on. She was already worshiped in the Uruk period, and appears in documents from many Mesopotamian cities from the third millennium BCE. She is also known from various works of Mesopotamian literature, such as the debate poem Debate between Sheep and Grain.

The logogram ^dŠE.TIR can be read as both Ezina and Ashnan. According to Jeremy Black, both are used interchangeably to refer to the same deity in modern publications. Frank Simons argues the latter can be understood as the "Akkadianised version" of Ezina. The Sumerian word ezina was also a common noun referring to grain. The Akkadian ašnan could be interpreted the same way. However, the precise etymology of both is uncertain. The goddess designated by these names was associated with grain and agriculture. Early on in her history, she was a major deity, but in later periods she was simply perceived as the divine hypostasis of grain. In addition to her primary role, she could be invoked alongside Nintur to stop post-natal bleeding.

It is possible that in art, Ashnan was depicted as a goddess surrounded by grain-like plants. In some cases this figure is depicted seated on a throne.

The compound theonym Ezina-Kusu, which combines the names of Ezina and Kusu, a goddess associated with ritual purification, is well attested. The Akkadian form Ashnan-Kusu is also known. The compound name already appears in sources from the Early Dynastic period. In most texts, it seemingly designates a deity analogous to Ezina, for example the hymnic composition preserved on the Gudea Cylinders states that "Ezina-Kusu, the pure stalk, will raise its head high in the furrows in Gu-edina", while The Debate between Sheep and Grain uses the double name interchangeably with that of the grain goddess. Frank Simons has suggested that Kusu was not a distinct goddess at first, but rather an epithet, and only developed into a separate figure at a later date. However, it has also been argued that Kusu treated as an epithet was not related to the purification goddess, and should be understood as a generic appellation, "goddess filled with purity". Ezina-Kusu is also attested as an epithet referring to Nisaba and Aruru in their respective vegetation-related roles.

Under the name Ezina the Mesopotamian grain goddess was already worshiped in the Uruk period. According to the Archaic City List, a settlement named after her existed somewhere in Mesopotamia, though the reading of its full name remains unknown. She is one of the oldest attested city goddesses, with Nisaba, Nanshe, Inanna of Uruk and Inanna of Zabalam being the only other ones present in texts of comparable age.

The twenty-seventh of the Early Dynastic Zame Hymns from Abu Salabikh is dedicated to Ezina. In this composition her cult center is the settlement AB׊UŠ (U₂; the reading of this toponym remains unknown). However, it is not mentioned in the closely related Temple Hymns or any other later sources. Ezina is also present in the Fara and Abu Salabikh god lists.

Evidence for the worship of the grain goddess under either of her names is also available from Lagash, Adab, Umma, Ur, Nippur and Shuruppak. Alfonso Archi notes that she also occurs in a bilingual lexical list from Ebla, which gives the equation ^dAšnan = A-za-na-an, but she is absent from the administrative texts from this city.

In the Ur III period a temple dedicated to her existed in Nippur, and offerings to her are mentioned in a text from Puzrish-Dagan. Joan Goodnick Westenholz suggested that she was worshiped in the temple of Kusu in Nippur, which according to Andrew R. George likely bore the ceremonial name Esaĝĝamaḫ, "house of the exalted purifier".