The clan Mackay derives from a branch of the Royal house of Moray, probably deriving its style Mac-icMorgainn from Morgund of Pluscarden, a prince of the house of Moray. The first historic Chief was Angus Du (1380-1429). He was assassinated, and the clan was ruled by his younger son, until the rightful heir obtained his release from captivity on the Bass Rock, 1437. The latter's son was Chief and led the clan in the cruel fight of Blair Tannic, Caithness.
In 1628 Sir Donald Mackay of Strathnaver, Chief of the clan, was created Lord Reay, with remainder to his heirs male bearing the name and arms of Mackay.
The major portion of the estates was sold in the seventeenth century to pay the cost of maintaining and transporting 2000 men whom Lord Reay recruited for foreign service to assist the Protestant cause in the great Thirty Years' War. The earliest Gaelic charter extant was granted by Donald, Lord of the Isles, to Brian Vicar Mackay in 1408.

Chief: Lord Reay.
Patronymic: Morair Maghrath.
Clan Seat: House of Tongue, Sutherland.
Slogan: Bratach bhan mhic Aoidh.
Plant: Great Bulrush.
Memorials: Kirk of Tongue.
Pipe Music: (1) Mackay's White Banner. (2) Mackay's March