Alan Breck Stewart (Gaelic: Ailean Breac Stiùbhart; c. 1711 – c. 1791) was a Scottish soldier and Jacobite. He was also a central figure in a murder case that inspired novels by Sir Walter Scott and Robert Louis Stevenson.
In accordance with the fosterage customs of the Highland clans, Alan Stewart and his brothers grew up under the care of their relative James of the Glen in Appin. His soubriquet, Breck, came from the Gaelic for "spotted", as his face bore scars from smallpox. Stewart enlisted in the British Army of George II in 1745, just before the Jacobite rising of that year. He fought at the Battle of Prestonpans, but deserted to the Highland Jacobites. He subsequently fought for the Jacobites, but after they were defeated at the Battle of Culloden he fled to France, accompanying his commander and clan captain, Colonel Charles Stewart of Ardshiel (Ardshiel was not the chief of the Appin Stewarts, but took command in absence of the true chief). After joining one of the Scottish regiments serving in the French Army, Stewart was sent back to Scotland to collect rents for the exiled clan leaders and to recruit soldiers for the French Crown.
On 14 May 1752, Colin Campbell of Glenure, the royal agent collecting rents from the Ardshiel Stewarts, was murdered. As Alan Stewart had previously publicly threatened Glenure and had enquired about his schedule for the day in question, a warrant was issued for his arrest. However, he evaded capture, and so was tried in absentia and sentenced to death. His foster father, James, was convicted as an accessory to the murder and hanged. Later investigations suggest that the murderer could not have been Stewart at all. In the murder of Glenure the British government saw the potential danger of Jacobite assassinations of their agents in the Highlands, on the one hand, and also a potential renewal of a Campbell/Stewart feud, on the other. The execution of James of the Glen increased the Stewarts' discontent, and locally, especially after he was immortalised in fiction, Alan Breck Stewart was portrayed as a romantic figure.