Alexander of Islay or Alexander MacDonald (died 1449; Scottish Gaelic: Alasdair MacDomhnaill, Dòmhnallach or MacDhòmhnaill) was a medieval Scottish nobleman who succeeded his father Domhnall of Islay as Lord of the Isles (1423–1449), later rising to the rank of Earl of Ross (1436–49).

[2] However, the destruction of the Albany Stewarts removed the main reason for the cooperation between the King and the Lord of the Isles.

[3] It is possible that, as Michael Brown believes, James acknowledged Alexander's control of the earldom of Ross as a reward for his support against Albany, in 1426.

[5] However, Richard Oram takes a different view, and sees Alexander's adoption of this title and occupation of much of the earldom as a provocation towards James, since it had passed to the crown after the death of John Stewart, Earl of Buchan and Ross in 1424, however, neither the Duke of Albany, nor his son, John had title superior to Donald, Lord of the Isles, and his son, Alexander.

Most of these men, including John Mór, seem to have been released within a short time, although James took a few back to the south with him.

[7] According to Michael Brown and the 17th century History of the MacDonalds, James attempted to do a deal with John Mór, probably offering him the Lordship of the Isles, to which he was heir and for which he had revolted against his brother Donald decades before.

His young cousin, Donald Balloch ("the Freckled"), son of Alexander's uncle John Mór, may have been seeking revenge for his father's death.

Alexander, meanwhile, was planning to support James Mór, son of Duke Murdoch, in his claim to the Scottish throne.

Although according to Walter Bower Alexander had 10,000 men, when the royal standard was unfurled the Chattan and Cameron kindreds switched over to the King.

Although Alexander got away, the king capitalized on his victory by marching further north and seizing the castles of Urquhart and Dingwall.

Alexander, who had probably fled to Islay, found himself in a very difficult position, and on 27 August 1429 surrendered to King James at Holyrood Abbey, near the burgh of Edinburgh.

(This is questionable as Lachlan Og was actually married to Catherine, daughter of Colin Campbell, 1st Earl of Argyll.

King James therefore arranged a reconciliation with Alexander, who was pardoned for past offences and released from captivity.

At least by this time, and possibly early in 1436, James finally acknowledged Alexander as earl of Ross, the only magnate who could now offer security in the north-eastern Highlands.

[16] Having achieved the chief object of his career, Alexander spent the last decade of his life consolidating his position in Ross.

The large number of charters issued by Alexander at Inverness is probably explained by his role as Justiciar of Scotia.

Alexander's move east led to less direct lordship in the west, his original political heartland.

Elizabeth, daughter of Alexander Seton, Lord Gordon, whom he was forced to marry by King James, either in later 1431 or 1432.