Archibald St Maur, 13th Duke of Somerset

Archibald Algernon Henry St. Maur, formerly Seymour, 13th Duke of Somerset, etc. (30 December 1810 – 28 Berkeley Square, London, Oct 1891) was the son of Edward St. Maur, 11th Duke of Somerset and Lady Charlotte Douglas-Hamilton. He was also a baronet. His motto, Foy Pour Devoir, "Faith for Duty", has been adopted by HMS Somerset (IV) by permission.

He was baptized on 17 June 1811 at St. George's, Hanover Square, London, and succeeded his brother Edward Seymour, 12th Duke of Somerset, in 1885. In his younger years, he had served as a captain in the Royal Horse Guards. He spent much of his life at Burton Hall, in The Wolds, managing the estate. He served as High Sheriff of Leicestershire for 1844.

Archibald died at his London home in Berkeley Square, unmarried and childless. He was buried in the churchyard at Maiden Bradley, Wiltshire on 16 January 1891. A memorial in the style of a grave was erected in the churchyard at Berry Pomeroy, Devon. His titles passed to his brother, Algernon St. Maur.