Alexander Og MacDonald (died 1299) also known as Alexander of the Isles was a 13th-century Hebridean magnate. With the death of his father in about 1293 MacDonald succeeded as Lord of Islay and the chiefship of the MacDonalds. During his tenure as chief the lands of his family fell prey to the powerful Alexander MacDougall Lord of Argyll the chief of the MacDougalls.