Lieutenant-Colonel Lord Ninian Edward Crichton-Stuart (15 May 1883 – 2 October 1915) was a British Member of Parliament killed in the First World War.
Lord Ninian was the second son of John Crichton-Stuart, 3rd Marquess of Bute and the Honourable Gwendolen Mary Anne Fitzalan Howard, daughter of Edward Fitzalan-Howard, 1st Baron Howard of Glossop. He was educated at Harrow School and Christ Church, Oxford. He was commissioned in 1903 into the 3rd Battalion of the Queen's Own Cameron Highlanders and then served for two years in 1st Battalion, the Scots Guards.
He left the army after his marriage to the Hon. Ismay Preston in 1906 to concentrate on politics. In 1907 he was adopted as the Unionist candidate for the United Boroughs of Cardiff, Cowbridge and Llantrisant. He lost the election to D.A. Thomas in January 1910 but was successful in winning the seat in the December 1910 election.
In 1912 he took command of the 6th Battalion, the Welsh Regiment. He was killed in action on 2 October 1915 during the Battle of Loos while leading the 6th Welsh in a night attack on the Hohenzollern Redoubt, near La Bassée, aged 32. He is buried at Bethune Town Cemetery. Lord Ninian is commemorated on Panel 8 of the Parliamentary War Memorial in Westminster Hall, one of 22 MPs that died during World War I to be named on that memorial. Lord Ninian is one of 19 MPs who fell in the war who are commemorated by heraldic shields in the Commons Chamber. A further act of commemoration came with the unveiling in 1932 of a manuscript-style illuminated book of remembrance for the House of Commons, which includes a short biographical account of the life and death of Lord Ninian.