A name of Gaelic origin, MacKenzie, or Mhic Coinneach in Gaelic, means 'son of Kenneth'. The family are said to be descended from Gilleoin of the Aird, referring to The Aird in Ross-shire, with lands extending across that ancient country to Kintail in the west. The Mackenzies tended to prosper as the Stuart monarchs persecuted the MacDonald Lords of the Isles in the 15th century. By the beginning of the 17th century, the Mackenzies had gained the Isle of Lewis from the Macleods and Lochalsh from the MacDonnells. The family had their western stronghold at Eilean Donan Castle, defended on their behalf by the Macraes, and a seat at Castle Leod in the east.
The Mackenzies of Kintail were granted the Earldom of Seaforth in 1623. The Seaforths embraced the Presbyterian church and signed the National Covenant in 1638, supporting the Covenanters against the Royalists until, shocked at the execution of King Charles I in 1649, they changed sides. By the later 17th century, the Seaforths were Jacobites and this cost them their Earldom in 1716. Later restored, the title became extinct within a generation. Mackenzies also hold the Earldom of Cromartie, it having been given to the lawyer Sir George Mackenzie in 1703. Other notable members of the clan are Surveyor General of India Colin Mackenzie (1754 - 1821), explorer Sir Alexander Mackenzie (1764 - 1820), fur trader Donald MacKenzie (1783 - 1851), Canadian radical politician William Lyon Mackenzie (1795 - 1861), Canadian Prime Minister Alexander Mackenzie (1822-92), US cattleman Murdo MacKenzie (1850 - 1939), Osgood Mackenzie (1842 - 1922), responsible for Inverewe Gardens, author Sir Compton Mackenzie (1883 - 1972), actor Alexander Mackenzie (1885 - 1965) and broadcaster Aggie MacKenzie (b.1954).