Thomas Barclay may refer to:
Thomas Barclay (scholar) ( 1570–1632), Scottish jurist, professor at Toulouse and Poitiers Thomas Barclay (diplomat) (1728–1793), American merchant, consul, diplomat Thomas Henry Barclay (1753–1830), New York lawyer, American loyalist, British official Thomas Barclay (minister) (1792–1873), minister in the Church of Scotland and Principal of the University of Glasgow Thomas Barclay (missionary) (1849–1935), British missionary to Formosa (Taiwan) Thomas Barclay (economic writer) (1853–1941), British Liberal Party MP for Blackburn 1910 Thomas Swain Barclay (1892–1993), professor of political science at Stanford University