Sweyn Estridsson Ulfsson was King of Denmark from 1047 until his death in 1076. He was the son of Ulf Thorgilsson and Estrid Svendsdatter, and the grandson of Sweyn Forkbeard through his mother's line. He was married at least two times, and fathered 20 children or more out of wedlock, including the five future kings Harald Hen, Canute the Saint, Oluf Hunger, Eric Evergood, and Niels.