Captain Sir John Hamilton, 1st Baronet (21 February 1726–24 January 1784) was a Royal Navy officer of the eighteenth century. He joined as a captain's servant in HMS Rippon in 1740. Hamilton fought in the War of Jenkins' Ear at the Battle of Cartagena de Indias in 1741 and then transferred to where he participated in the unsuccessful Invasion of Cuba. He was promoted to midshipman in HMS Success in 1742, and was promoted to lieutenant while serving on in 1747. Having served in a variety of ships as a lieutenant, Hamilton was promoted to commander in 1762. After initially commanding he served in and HMS Merlin on the Newfoundland Station before being promoted to post captain in 1766.