In Norse mythology, the Nine Mothers of Heimdallr are nine sisters who gave birth to the god Heimdallr. The Nine Mothers of Heimdallr are attested in the Prose Edda, written in the 13th century by Snorri Sturluson; in the poetry of skalds; and possibly also in a poem in the Poetic Edda, a book of poetry compiled in the 13th century from earlier traditional material. Scholars have debated what being "born of nine mothers" implies and have sought to connect the notion to other European folk motifs. Scholars have theorized that Heimdallr's Nine Mothers may be identical to the Nine Daughters of Ægir and Rán, who personify waves. In turn, Heimdallr would be born of the sea.

Norse, Nordic, or Scandinavian mythology, is the body of myths belonging to the North Germanic peoples, stemming from Old Norse religion and continuing after the Christianization of Scandinavia, and into the Nordic folklore of the modern period. The northernmost extension of Germanic mythology and stemming from Proto-Germanic folklore, Norse mythology consists of tales of various deities, beings, and heroes derived from numerous sources from both before and after the pagan period, including medieval manuscripts, archaeological representations, and folk tradition. The source texts mention numerous gods such as the thunder-god Thor, the raven-flanked god Odin, the goddess Freyja, and numerous other deities.