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

His younger brother, John Hamilton, married Lady Christian Lindsay (a daughter of the 17th Earl of Crawford).

[2] Following his mother's death in 1635, in 1640 his father married Lady Jean Gordon (a daughter of the 2nd Marquess of Huntly).

From this marriage, he had a younger half-sister, Lady Margaret Hamilton (who married John Keith, 1st Earl of Kintore).

[3] His paternal grandparents were Thomas Hamilton, 1st Earl of Haddington and the former Margaret Foulis of Colinton.