Alexander Montgomerie, 10th Earl of Eglinton (10 February 1723 – 25 October 1769), was a Scottish peer. Eglinton was the son of The 9th Earl of Eglinton. His mother, who was the third wife of the 9th Earl, was Susanna, Countess of Eglinton, the society beauty. He was the Grand Master Mason of the Grand Lodge of Scotland from 1750 to 1751.