In Norse mythology, Hjúki and Bil are a brother and sister pair of children who follow the personified Moon, Máni, across the heavens. Both Hjúki and Bil are solely attested in the Prose Edda, written in the 13th century by Snorri Sturluson. Scholarly theories that surround the two concern their nature, their role as potential personifications of the craters on the Moon or its phases, and their relation to later folklore in Germanic Europe. Bil has been identified with the Bilwis, an agriculture-associated figure that is frequently attested in the folklore of German-speaking areas of Europe.