Amy of Garmoran also known as Amie MacRuari and Euphemia was a 14th-century Scottish noblewoman who was the sister of Raghnall mac Ruaidhri, Lord of Garmoran and the spouse of John of Islay. After her marriage had produced three sons, the ambitious John of Islay divorced her in order to remarry and cement his links with the House of Stewart. She then retired to her estates in the Highlands and Islands, and completed various ecclesiastical and other building projects. Her son Ranald was the progenitor of Clanranald.

John of Islay was the Lord of the Isles (1336–1386) and chief of Clan Donald. In 1336, he styled himself Dominus Insularum, although this was not the first ever recorded instance of the title in use. Some modern historians nevertheless count John as the first of the later medieval Lords of the Isles, although this rather broad Latin style corresponds roughly with the older Gaelic title Rí Innse Gall, in use since the Viking Age. For instance, the even more similar Latin title dominus de Inchegal, applied to Raghnall Mac Somhairle in the mid-12th century. In fact John is actually styled Rí Innsi Gall or King of the Isles shortly after his death in a contemporary entry in the Irish Annals of Ulster. Clan Donald considers the title "Lord of the Isles" to have been in use at least since Angus Mor Macdonald, who died in 1293, and the title "King of the Isles" in use since Somerled, the Norse-Gael who forged the Kingdom of the Isles in the 12th century.