In Norse mythology, Nótt (Old Norse "night") is night personified, grandmother of Thor. In both the Poetic Edda, compiled in the 13th century from earlier traditional sources, and the Prose Edda, written in the 13th century by Snorri Sturluson, Nótt is listed as the daughter of a figure by the name of Nörvi (with variant spellings) and is associated with the horse Hrímfaxi, while the Prose Edda features information about Nótt's ancestry, including her three marriages. Nótt's third marriage was to the god Dellingr and this resulted in their son Dagr, the personified day (although some manuscript variations list Jörð as Dellingr's wife and Dagr's mother instead). As a proper noun, the word nótt appears throughout Old Norse literature.
In stanza 24 of the poem Vafþrúðnismál, the god Odin (disguised as "Gagnráðr") asks the jötunn Vafþrúðnir from where the day comes, and the night and its tides. In stanza 25, Vafþrúðnir responds:
In stanza 14 of the Vafþrúðnismál, Odin states that the horse Hrímfaxi "draws every night to the beneficent gods" and that he lets foam from his bit fall every morning, from which dew comes to the valleys. In stanza 30 of the poem Alvíssmál, the god Thor asks the dwarf Alvíss to tell him what night is called in each of the nine worlds, whom "Nórr" birthed. Alvíss responds that night is referred as "night" by mankind, "darkness" by the gods, "the masker" by the mighty Powers, "unlight" by the jötunn, "joy-of-sleep" by the elves, while dwarves call her "dream-Njörun" (meaning "dream-goddess").