Thomas Smyth (1740 – 14 January 1785) was an Irish politician.
He was appointed High Sheriff of County Limerick for 1770.
He was succeeded in the constituency and in militia by his brother John Prendergast Smyth.
His paternal grandparents were Thomas Smyth, Bishop of Limerick, and Dorothea Burgh (daughter of Ulysses Burgh), and his paternal uncles included the lawyer George Smyth and Arthur Smyth, Archbishop of Dublin.
Smyth died unmarried at Bordeaux, but fathered four children, all of whom bore the surname Stuart, including the Indian army officer Charles "Hindoo" Stuart.