Sweyn II of Denmark
Sweyn's daughter, Estrid Svendsdatter, was the mother of King Sweyn II of Denmark. Her descendants continue to reign in Denmark to this day. One of them, Margaret of Denmark, married James III of Scotland in 1469, introducing Sweyn's bloodline into the Scottish royal house. After James VI of Scotland inherited the English throne in 1603, Sweyn's descendants became monarchs of England again.