Rob Roy, the nickname of Robert MacGregor (1671-1734), a Scottish Highlands chief and outlaw. He was so called because of his red hair, “roy” being Scottish Gaelic for “red.” At the age of 22 Rob Roy became chief of the MacGregor clan, which made its living from cattle stealing and from extorting fees from cattle owners to “protect” their herds from brigands. In 1693 the government declared the MacGregors outlaws, and he assumed his mother's name, Campbell. Despite the clan's being outlawed, Rob Roy was able to continue his activities without hindrance, because the Duke of Montrose and several other powerful lords found him a useful ally.

Rob Roy was evicted from his lands in 1712 when he lost the protection of Montrose. He continued his extortion and cattle raids until 1722, when he was captured, taken to London, and imprisoned. He was pardoned in 1727, and lived out his last years quietly. Sir Walter Scott's Rob Roy (1817) glamorizes his exploits.