Sir Lancelot Douglas Carnegie GCVO KCMG (Edinburgh, 26 December 1861 – London, 15 October 1933), was a British diplomat. He was the second son of the 9th Earl of Southesk, and the eldest son by his second marriage (1860) to Lady Susan Murray (died 1915), eldest daughter of Alexander Murray, 6th Earl of Dunmore. His matrilineal great-uncle was the diplomat and statesman Sidney Herbert, Lord Herbert of Lea.