Sweyn Forkbeard (Old Norse: Sveinn Tjúguskegg; Danish: Svend Tveskæg; 960 – 3 February 1014) was king of Denmark, England, and parts of Norway. His name appears as Swegen in the Anglo-Saxon Chronicle. He was the son of King Harald Bluetooth of Denmark, and the father of Cnut the Great.
In the mid-980s, Sweyn revolted against his father and seized the throne. Harald was driven into exile and died shortly afterwards in November 986 or 987. In 1000, with the allegiance of Trondejarl, Eric of Lade, Sweyn ruled most of Norway.
After several invasions of England, Sweyn was finally successful and on Christmas Day 1013 was declared King of England. Based in Gainsborough, Lincolnshire, Sweyn began to organise his vast new kingdom, but he died there on 3 February 1014, having ruled England for only five weeks.
Sweyn's elder son, Harald II, succeeded him as King of Denmark, but the Danish fleet in England proclaimed his younger son Cnut king. In England, the councillors had sent for Æthelred, who upon his return from exile in Normandy in the spring of 1014 managed to drive Cnut out of England. But Cnut returned and became King of England in 1016, eventually also ruling Denmark, Norway, parts of Sweden, Pomerania, and Schleswig.
Sweyn's son Cnut and Cnut's own sons Harold Harefoot and Harthacnut ruled England for 26 years. After Harthacnut's death, the English throne reverted to the House of Wessex in the person of King Edward the Confessor (reigned 1042–1066).