Ranald MacDonald of Smerby was a son of James MacDonald, 6th of Dunnyveg and Agnes Campbell, daughter of Colin Campbell, 3rd Earl of Argyll. He was granted Smerby Castle from his father. He was a hostage for the good behaviour of his family together with his nephew James held by Sir Lachlan Mor Maclean. He was in charge of the garrison of troops within Loch Gorm Castle and surrendered the castle to Sir John Campbell of Cawdor on 28 January 1615. Ranald died in 1616, and was buried at Saddell Abbey.
By his wife, a daughter of Bannatyne of Kames, their children were: