In Germanic mythology, Sigmund (Old Norse: Sigmundr [ˈsiɣˌmundz̠], Old English: Sigemund) is a hero whose story is told in the Völsunga saga. He and his sister, Signý, are the children of Völsung and his wife Hljod. Sigmund is best known as the father of Sigurð the dragon-slayer, though Sigurð's tale has almost no connections to the Völsung cycle except that he was a dragonslayer. Völsunga saga. In the Völsunga saga, Signý marries Siggeir, the king of Gautland (modern Västergötland).
https://en.wikipedia.org/wiki/Sigmund