Thomas Duncan ARA RSA was a Scottish portrait and historical painter.

Duncan was born in Kinclaven, Perthshire on 4 May 1807.

Educated at the Perth Academy, he began studying law, but abandoned it for art. 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.

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.

He died of a brain tumour in Edinburgh on 25 April 1845.