Magnus Olafsson, King of Mann and the Isles
Magnús Óláfsson (died 24 November 1265) was a King of Mann and the Isles. He was a son of Óláfr Guðrøðarson, King of the Isles, and a member of the Crovan dynasty. Magnús' realm encompassed Mann and parts of the Hebrides. Some leading members of Magnús' family—such as his father—styled themselves "King of the Isles"; other members—such as Magnús and his brothers—styled themselves "King of Mann and the Isles". Although kings in their own right, leading members of the Crovan dynasty paid tribute to the Kings of Norway and generally recognised a nominal Norwegian overlordship of Mann and the Hebrides.

In 1237, Óláfr died and was succeeded by his elder son, Haraldr, who later drowned in 1248. The kingship was then taken up by his brother, Rǫgnvaldr Óláfsson. After a reign of only weeks, Rǫgnvaldr was slain and the kingship was taken up by Haraldr Guðrøðarson, a descendant of Óláfr's half-brother and deadly rival, Rǫgnvaldr Guðrøðarson, King of the Isles. After a short reign, this Haraldr was removed from power by his overlord, Hákon Hákonarson, King of Norway. In Haraldr's absence, Magnús and a relation of his, Eóghan Mac Dubhghaill, King in the Isles, unsuccessfully attempted to conquer Mann. A few years later, Magnús successfully made his return to the island and was proclaimed king.

In the 1240s, following attempts to purchase the Isles from Hákon, Alexander II, King of Scots resorted to warfare to win the region. His death in 1249 brought an abrupt end to his westward invasion, and it was not until the 1260s that a Scottish king again attempted to impose his authority into the Isles. In 1261, Alexander II's son and successor, Alexander III, attempted to purchase the Isles without success, before Scottish forces raided into the Hebrides. Hákon's response to Scottish aggression was to organise a massive fleet to re-assert Norwegian authority. In the summer of 1263, the fleet sailed down through the Hebrides. Although his forces gained strength as they sailed southwards, the Norwegian king received only lukewarm support from many of his Norse-Gaelic vassals—in fact, Magnús was one of the few who came out whole-heartedly for Hákon. At one point during the campaign, Hákon sent Magnús and some other vassals raiding deep into Lennox. Meanwhile, the main Norwegian force was occupied with the Battle of Largs—a famous, but inconclusive series of skirmishes against the Scots. Following this action, Hákon's demoralised fleet returned home having accomplished little. Not long after Hákon's departure and death, Alexander launched a punitive expedition into the Hebrides, and threatened Mann with the same. Magnús' subsequent submission to the Scottish king, and the homage rendered for his lands, symbolises the failure of Hákon's campaign, and marks the complete collapse of Norwegian influence in the Isles.

Magnús, the last reigning king of his dynasty, died at Castle Rushen in 1265, and was buried at the Abbey of St Mary of Rushen. At the time of his death, he was married to Eóghan's daughter Máire. In the year after his death, the Hebrides and Mann were formally ceded by King of Norway to the King of Scots. Ten years after Magnús' death, Guðrøðr, a bastard son of his attempted to establish himself as king on Mann. Guðrøðr's revolt was quickly and brutally crushed by Scottish forces, and the island remained part of the Kingdom of Scotland. By the 1290s, the Hebridean portion of Magnús' former island-kingdom had been incorporated into a newly created Scottish sheriffdom.