4. Rǫgnvaldr Óláfsson was the King of Mann and the Isles for less than a month in 1249 CE, the last Norse king to suffer regicide
Rǫgnvaldr Óláfsson was a member of the Crovan dynasty, the son of Óláfr Guðrøðarson, King of Mann and the Isles, and himself King between May 6 and May 30, 1249 CE. Although kings in their own right, the King of Mann and the Isles typically paid homage and tribute to the King of Norway as a higher authority. Upon the death of King Óláfr in 1237, Rǫgnvaldr Óláfsson’s eldest brother, Haraldr, assumed the throne, continuing to fight with several family members before being lost at sea in 1248 whilst returning home from Norway. In the course of the voyage, it is recorded the ship foundered off the coast of Shetland with all aboard killed. In response to the vacated position, Rǫgnvaldr Óláfsson claimed the crown and formally became King of the Isles on May 6, 1249.
However, his reign was short-lived, for on May 30, King Rǫgnvaldr was slain by a knight named Ívarr. Although the precise identity of Ívarr is unclear, historical evidence strongly suggests that he was in the employ of Rǫgnvaldr’s first cousin Haraldr Guðrøðarson, who conspired against his relative to seize the throne himself. Despite this long history of factional violence, Rǫgnvaldr’s murder was the last known instance of regicide in the Norse-Gaelic territories. Haraldr’s own reign did not last long for in 1250 he was recalled to Norway to answer for his unjust seizure of the kingdom and Rǫgnvaldr Óláfsson’s brother, Magnús, was seated in his stead.