Thomas Duncan ARA RSA (4 May 1807 – 25 April 1845) was a Scottish portrait and historical painter.

Beginning under the instruction of Sir William Allan, he attained early distinction as a delineator of the human figure; and his first pictures established his fame so completely, that at a very early age he was appointed professor of coloring and afterwards of drawing, in the Trustees' Academy of Edinburgh.

[2] In the 1830s, his address is given as 1 Darnaway Street, a large Georgian flat on the edge of the Moray Estate in the west end of Edinburgh's New Town.

In 1840, Duncan painted one of his finest pictures, Charles Edward Stuart and the Highlanders entering Edinburgh after the Battle of Prestonpans, which secured his election as an associate of the Royal Academy in 1843.

In the same year, he produced his picture of Charles Edward asleep after Culloden, protected by Flora MacDonald, which, like many other of his works, has been often engraved.