Originally from the shores of Loch Fyne in Argyll, the MacEwan clan are descendants of Ewen of Otter. They shared a common heritage with the MacLachlan and MacNeil families until the last chief Sween MacEwen became Baron of Otter. He was the last chief as the clan became dependants of the Campbells. The clan scattered and many MacEwans became outlaws and the Earls of Argyll (Campbells) were made responsible for their behaviour.
Elspeth MacEwan was made infamous by being the last person to be executed for witchcraft in Scotland (1698).
In the 19th century, William McEwan (1827 - 1913) became a noted Edinburgh brewer. More recently, in 1953, John Helias Finnie McEwen, Under-Secretary of State for Scotland, 1939 - 1940, was made Baronet of Marchmont and Bardrochat, and several members of this branch of the family have been notable in music and the arts.