John Mor MacDonald (Scottish Gaelic: Seán Mór Mac Dhòmhnaill), fl.
John Mor was a son of Donald Balloch MacDonald and Johanna, daughter of Conn O'Neill of Edenduffcarrick.
In 1493, with John of Islay being required to forfeit his title of Lord of the Isles and pay homage to King James IV of Scotland, the King garrisoned and provisioned Tarbert and Dunaverty Castle with royal forces in 1494.
Sir John Macdonald ignored the summons and continued to reside at Islay.
John Cathanach's remaining son, Alexander Carragh, fled to Ireland and became the next chief of the clan and 5th earl of Dunnyveg.