Somhairle Buidhe Mac Domhnaill (English: Somhairle of the yellow hair, son of Donnell, anglicized Sorley Boy MacDonnell, or MacDonald in Scotland) (c. 1505 - 1590), Scoto-Irish chieftain, is the son of Alexander MacDonnell, lord of Islay and Kintyre (Cantire), and Catherine, daughter of the Lord of Ardnamurchan.

MacDonnell is best known for establishing the MacDonnell clan in Antrim and resisting the campaign of Shane O'Neill and the English crown to expel the clan from Ireland.