king of Norway (1162–84) who used church support to gain the throne (1162) and become the nation's first crowned monarch (1163). After 1177 his rule was challenged by his rival Sverrir (Sverrir Sigurdsson), whose forces killed Magnus in battle.

The son of Erling the Crooked, Magnus became king in 1162 when his supporters, led by his father, defeated the forces of the incumbent king, Haakon II Sigurdsson. Magnus' father served as regent until 1164 and remained the real power behind the throne until his death in 1179.

In 1163 Erling arranged with the Norwegian archbishop Eystein Erlandsson to have Magnus crowned in exchange for royal support of the Roman Catholic Church. After Magnus' supporters defeated his rivals, the Birchlegs, in 1177, the King's forces were badly defeated (1179) by the pretender Sverrir, who included the remnants of the Birchlegs among his followers. Magnus then fled to Denmark, and Sverrir became ruler of much of Norway. When Magnus attempted to regain control of the country in 1184, aided by the Danish king Canute IV, he was again defeated by Sverrir's forces and slain in battle.