Magnus Erlingsson

Magnus Erlingsson (Old Norse: Magnús, 1156 – 15 June 1184), also known as Magnus V, was a king of Norway during the civil war era in Norway. He helped to establish primogeniture in royal succession in Norway. King Magnus was killed in the Battle of Fimreite in 1184 against the forces of Sverre Sigurdsson who became King of Norway.

Source: Wikipedia — https://en.wikipedia.org/wiki/Magnus_Erlingsson