Thomas Hamilton, 3rd Earl of Haddington

Thomas Hamilton, 3rd Earl of Haddington (1626 – 8 February 1645) was a short-lived Scottish nobleman.

Haddington was born in 1626, eldest son of Thomas Hamilton, 2nd Earl of Haddington and Lady Mary Stuart, a daughter of Esmé Stewart, 1st Duke of Lennox.

Lord Haddington was a minor when he succeeded his father. The latter having been killed in an explosion at Dunglass Castle during the Bishops' Wars. Haddington travelled to the continent to further his education. While in France he met Henriette de Coligny, daughter to Gaspard de Coligny, Duc de Châtillon, Marshal of France. Henriette de Coligny was eight years senior to Haddington, but nevertheless a marriage was contracted between them in 1643.

Haddington and his bride returned to Scotland, where he involved himself with the Covenanters. Haddington died, while still underage of Consumption on 8 February 1645, without issue. His countess returned to France where she remarried to Gaspard de Champagne, Comte de la Suze, and died in 1673.

Lord Haddington was succeeded by his brother John Hamilton, 4th Earl of Haddington.