There are at least four bands sharing this name:

1.) (Pagan) black metal band from Buenos Aires, Argentina. Formed in 2007, split up in 2015 and re-activated in 2020. At this time, the only member is Lord Azog.

2.) Æsir, UK metal band from Cornwall, England. Founded in 2007, changed the name as Morgawr in 2009. Lyrical themes are influenced by Norse mythology, while the musical style draws heavy influence on Scandanavian folk, symphonic folk metal, epic black metal and death metal influences. The songs are described to be heavy, melodic and catchy. Mixing harsh vocals with shrill screams, heavy riffs with acoustic folk sections and speed metal drumming, a whole range of musical styles are also covered.

3.) Spanish power/progressive metal band from Donostia-San Sebastian, Basque Country. Formed in 2005.

4.) US thrash metal band from Mahopac, New York. Active from 1987 to 1988. Changed name as Paralysis

The Æsir (plural of the Old Icelandic Áss: "God") are the members of a family of gods such as Þórr or Óðinn attested both in the Poetic and the Prose Edda. The term is however sometimes used (Especially in the Prose Edda) to refer to all the Norse gods in general including thus the gods of the Vanir family.
Long ago, now only remembered in Norse mythology, the ÆSIR existed as the sacred Gods of Power and War.
Fearless and proving their might countless times in history, the ÆSIR reside among the Asgardian golden halls of Valhalla, awaiting the day when blood is spilt in their name once more... Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.