General Sir James Macdonell or Macdonnell GCB KCH (1781 – 15 May 1857) was the third son of Duncan Macdonnell of Glengarry. Alexander Ranaldson Macdonell of Glengarry was his elder brother.
In 1794, he was a lieutenant in the 78th (Highlanders) Regiment of Foot; in 1795, he was Captain in the 17th Dragoons. He joined the 19th Foot in 1796; he was major in the 78th Foot, and was awarded the Army Gold Medal for Maida in 1806. He joined the Coldstream Guards in 1811 as a Lieutenant Colonel, and served in the Peninsular War.
He is best known for his command of the light troops defending Hougoumont at the battle of Waterloo, 1815, where he fought with great distinction, including leading the vital closing of the gates, with his sergeant, James Graham. He was wounded slightly in the battle.
He commanded the Brigade of Guards in Canada from 1838 to 1841. He was then successively given the colonelcy of the 79th Regiment of Foot (Cameron Highlanders) from 1842 to 1849 and the 71st (Highland) Regiment of Foot from 1849 until his death in 1857. He was promoted full general in 1854.