Which Viking king ruled England, Denmark and Norway as part of a North Sea empire?

Cnut the Great ruled England, Denmark, and Norway as part of a North Sea empire.

Cnut, also spelled Canute, became king of England in 1016 after defeating Edmund Ironside. He inherited or secured the Danish throne in 1018 and conquered Norway in 1028, creating a powerful but short-lived political union around the North Sea. His empire also included influence over parts of Sweden and the western Scandinavian world.

Cnut supported the Christian church and presented himself as a legitimate Christian king rather than merely a Viking conqueror. He made pilgrimages to Rome, issued laws, and appointed officials to govern his territories. His marriage to Emma of Normandy strengthened his position in England and connected him to important continental politics.

The famous story in which Cnut supposedly tried to command the tide is often misunderstood. Medieval accounts present it as a demonstration that even a king lacks divine power, not as a serious claim that he could control the sea. Cnut’s empire weakened after his death in 1035 because it depended heavily on his personal authority.