General John Mostyn (c.1709 – 16 February 1779) was a British soldier, MP and colonial administrator. He was a younger son of Sir Roger Mostyn, 3rd Baronet and educated at Westminster School and Christ Church, Oxford. Mostyn served as Governor of Menorca for a ten-year period between 1768 and 1778. It was a titular role and Mostyn was not in residence on the island, which meant that his deputy was in effective charge – from 1774 this was James Murray, his eventual successor who was forced to surrender the island in 1782 to a Spanish force. He died unmarried.