Lieutenant-General Francis Humberston Mackenzie, 1st Baron Seaforth, was a British politician, soldier, and botanist. He was Chief of the Highland Clan Mackenzie, as which he raised the renowned 78th (Highlanders) Regiment of Foot.

Clan Mackenzie is a Scottish clan, traditionally associated with Kintail and lands in Ross-shire in the Scottish Highlands. Traditional genealogies trace the ancestors of the Mackenzie chiefs to the 12th century. However, the earliest Mackenzie chief recorded by contemporary evidence is Alexander Mackenzie of Kintail who died some time after 1471. Traditionally, during the Wars of Scottish Independence, the Mackenzies supported Robert the Bruce, but feuded with the Earls of Ross in the latter part of the 14th century. During the 15th and 16th-centuries the Mackenzies feuded with the neighboring clans of Munro and MacDonald. In the 17th century the Mackenzie chief was made Earl of Seaforth in the peerage of Scotland. During the Scottish Civil War of the 17th century the Mackenzies largely supported the Royalists. During the Jacobite rising of 1715 the chief and clan of Mackenzie supported the Jacobite cause. However, during the Jacobite rising of 1745 the clan was divided with the chief, Kenneth Mackenzie, Lord Fortrose, supporting the British-Hanoverian Government and his relative, George Mackenzie, 3rd Earl of Cromartie, supporting the Jacobites.