Olaf II Haroldsson (ca. 990-1030), also called St. Olaf, was king of Norway from 1015 to 1028. The first king of the whole of Norway, he organized its final conversion and its integration into Christian Europe.

Olaf was a son of Harold Graenske, a magnate, or kinglet, in eastern Norway and presumably related to Harold I Fairhair, the first king of Norway. From an early age he partook in Viking expeditions to the Baltic, to England (1009-1011), and to the north of France (1012), where he was baptized at Rouen, having been converted either in England or in France. He returned to England, supporting Ethelred against Cnut the Great (1014), and was back in Norway in 1015.

Western Norway was ruled by the two Lade jarls. This was the inheritance of King Harold Fairhair. Eastern Norway was ruled by a number of kinglets. After the death of King Olaf Trygvasson in the battle...