Heimdall is said to have been born from nine mothers.
Norse mythology describes Heimdallr as the son of nine sisters, a remarkable origin unlike the usual single-parent genealogies of the gods. The Prose Edda preserves the formula that he is the offspring of nine mothers and the son of nine sisters. Another poetic description calls him the son of “eight mothers plus one.”
The names of the nine mothers appear in the poem Völuspá hin skamma, preserved within the Poetic Edda tradition. They include Gjálp, Greip, Eistla, Eyrgjafa, Ulfrún, Angeyja, Imðr, Atla, and Járnsaxa. Several of these names also occur elsewhere as names of female jötnar, which makes the genealogy difficult to interpret.
Some scholars identify the nine mothers with the nine daughters of the sea-god Ægir and the goddess Rán, who personify waves. On that reading, Heimdallr is symbolically born from the sea. The identification is debated because the two groups’ names do not perfectly match, but the number nine is explicit in the principal textual descriptions. Heimdallr later guards the gods’ realm and sounds his horn at Ragnarök.