Earl of Haddington is a title in the Peerage of Scotland. It was created in 1627 for the noted Scottish lawyer and judge Thomas Hamilton, 1st Earl of Melrose. He was Lord President of the Court of Session from 1616 to 1625. Hamilton had already been created Lord Binning in 1613 and Lord Binning and Byres, in the County of Haddington, and Earl of Melrose, in the County of Roxburgh, in 1619. These titles were also in the Peerage of Scotland. The title of the earldom derived from the fact that he was in possession of much of the lands of the former Melrose Abbey. However, Hamilton was unhappy with this title and wished to replace it with "Haddington". In 1627 he relinquished the earldom of Melrose and was instead created Earl of Haddington, with the precedence of 1619 and with limitation to his heirs male bearing the surname of Hamilton. This derived from the fact that he considered it a greater honour to take his title from a county rather than from an abbey. Hamilton was a member of the prominent Scottish family of that name and descended from John de Hamilton, younger son of Walter de Hamilton, who was granted the feudal barony of Cadzow and who is also the ancestor of the Dukes of Hamilton and Dukes of Abercorn.

Thomas Hamilton, 1st Earl of Haddington, designated before his peerage as 'of Drumcarny, Monkland, and Binning', was a Scottish administrator, Lord Advocate, judge, and Lord Lieutenant of Haddingtonshire.