Charles John Gardiner, 1st Earl of Blessington was an Irish peer best known for his marriage to Margaret Farmer, whom he married at St Mary's, Bryanston Square, London, on 16 February 1818. He was elected an Irish representative peer in 1809, created Earl of Blessington in 1816, and inherited the title of Viscount Mountjoy in 1798. He was present at the trial of Queen Caroline.