Urðarbrunnr is a well in Norse mythology. Urðarbrunnr is attested in the Poetic Edda, compiled in the 13th century from earlier traditional sources, and the Prose Edda, written in the 13th century by Snorri Sturluson. In both sources, the well lies beneath the world tree Yggdrasil, and is associated with a trio of norns. In the Prose Edda, Urðarbrunnr is cited as one of three wells existing beneath three roots of Yggdrasil that reach into three distant, different lands; the other two wells being Hvergelmir, located beneath a root in Niflheim, and Mímisbrunnr, located beneath a root near the home of the frost jötnar. Scholarly theory and speculation surrounds the well.

Old Norse, Old Nordic, or Old Scandinavian is a stage of development of North Germanic dialects before their final divergence into separate Nordic languages. Old Norse was spoken by inhabitants of Scandinavia and their overseas settlements and chronologically coincides with the Viking Age, the Christianization of Scandinavia and the consolidation of Scandinavian kingdoms from about the 8th to the 15th centuries.