Sir Thomas de Brus (c. 1284, Carrick, Ayrshire – 17 February 1307) was a son of Robert de Brus, 6th Lord of Annandale and Margaret, Countess Of Carrick and thus a younger brother of King Robert I of Scotland. He supported his brother in the struggle against the English conquest, ultimately being captured by the MacDoualls at Loch Ryan, Galloway, Scotland and later executed by the English. ^[1]

This article needs additional citations for verification. (May 2021)

Thomas was married to Helen Erskine.

During the Scottish Wars of Independence, Thomas and his brother Alexander de Brus, along with Malcolm McQuillan, Lord of Kintyre, an Irish sub king, and Sir Reginald de Crawford, sailed an invasion force consisting of eighteen galleys and 1000 Irishmen into the harbor at Loch Ryan. Their force was quickly overwhelmed by Gallowaymen, led by Dungal MacDouall, a supporter of the Balliols, Comyns and King Edward I of England, in the subsequent Battle of Loch Ryan. All the leaders were captured and only two galleys escaped. The Irish sub king and Malcolm McQuillan were executed immediately; Thomas, Alexander, and Reginald de Crawford were sent to Carlisle, England, where they were hanged, drawn, and beheaded a few days after the battle.^[2]