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.

In Norse mythology, Bifröst, also called Bilröst, is a burning rainbow bridge that reaches between Midgard (Earth) and Asgard, the realm of the gods. The bridge is attested as Bilröst in the Poetic Edda, compiled in the 13th century from earlier traditional sources; as Bifröst in the Prose Edda, written in the 13th century by Snorri Sturluson; and in the poetry of skalds. Both the Poetic Edda and the Prose Edda alternately refer to the bridge as Ásbrú.