Lt.-General Godfrey Bosville Macdonald, 3rd Baron Macdonald of Sleat (14 October 1775 Edinburgh, Scotland - 13 October 1832 Bridlington, England) was the second son of Alexander Macdonald, 1st Baron Macdonald (c.1745-1795) and Elizabeth Diana Bosville (1748–1789). He succeeded his elder brother Alexander Macdonald, 2nd Baron Macdonald, in the barony on 19 June 1824, after the former died unmarried and without legitimate issue.
He was educated at Harrow School, Harrow on the Hill, London, England. He matriculated Oriel College, University of Oxford, Oxford, Oxfordshire, England, on 17 December 1792.
He gained the rank of Ensign, in 1794, serving in the Loyal Kelso Regiment and the King's Royal Rifle Corps. He then gained the rank of Captain, in 1796, serving in the 86th Regiment of Foot and the rank of Lieutenant, that same year, while serving with the 70th (Surrey) Regiment of Foot. He then gained the ranks of Major, in the service of the 55th Regiment of Foot, and Lieutenant-Colonel, in the service of the South Wales Borderers. He gained the rank of Lieutenant-Colonel in 1808 in the service of the Grenadier Guards. He gained the ranks of Brevet Colonel, in 1811, the rank of Major-General, in 1814, and of Lieutenant-General, in 1830.