The Honourable John Mordaunt (c. 1709 – 1767), was a British soldier and politician. Mordaunt was the second son of John Mordaunt, Viscount Mordaunt and Frances Powlett. He was a cornet in the Royal Horse Guards from 1726 to 1736. He married Hon. Mary Howe (d. 1749), the daughter of Scrope Howe, 1st Viscount Howe, in November 1735, and later Elizabeth Hamilton, but left no children. In 1745, he rejoined the Army to serve as the lieutenant colonel of the Duke of Kingston's Regiment of Light Horse, which he commanded at Culloden.