Óláfr Guðrøðarson (died 1237) (Scottish Gaelic: "Amhlaibh Dubh"), also known as Olaf the Black, was a thirteenth-century King of the Isles, and a member of the Crovan dynasty. He was a son of Guðrøðr Óláfsson, King of the Isles and Fionnghuala Nic Lochlainn. Óláfr was a younger son of his father; Óláfr's elder brother, Rǫgnvaldr, probably had a different mother. According to the "Chronicle of Mann", Guðrøðr appointed Óláfr as heir since he had been born "in lawful wedlock". Whether or not this is the case, after Guðrøðr's death in 1187 the Islesmen instead appointed Rǫgnvaldr as king, as he was a capable adult and Óláfr was a mere child. Rǫgnvaldr ruled the island-kingdom for almost forty years, during which time the half-brothers vied for the kingship.