In Norse mythology, Eir is a goddess or valkyrie associated with medical skill. Eir is attested in the Poetic Edda, compiled in the 13th century from earlier traditional sources; the Prose Edda, written in the 13th century by Snorri Sturluson; and in skaldic poetry, including a runic inscription from Bergen, Norway from around 1300. Scholars have theorized about whether these three sources refer to the same figure, and debate whether Eir may have been originally a healing goddess or a valkyrie. In addition, Eir has been compared to the Greek goddess Hygieia.

Æsir or ēse are gods in Germanic paganism. In Old Nordic religion and mythology, the precise meaning of the term "Æsir" is debated, with it being able to refer to both the gods in general or specifically to one of the main families of gods, in contrast to the Vanir, with whom they waged war, ultimately leading to a joining of the families. The term can further be used to describe local gods that were believed to live in specific features in the landscape such as fells. In the Old English Wið færstice, the Ēse are referred to, along with elves, as harmful beings that could cause a stabbing pain, although exactly how they were conceived of by the author of the text is unclear.