Louis d'Armagnac, Duke of Nemours (1472; Normandy, France – 28 April 1503; Cerignola, Italy), was a French nobleman, politician and military commander who served as Viceroy of Naples from 1501-1503, during the Third Italian War.

He was known for most of his life as the Count of Guise, and inherited the Duchy of Nemours following his brother Jean's death in 1500.

[1] Louis was the third son of Jacques d'Armagnac, Duke of Nemours and Louise of Anjou.

[2] In 1491, he was made Count of Guise,[2] a title last held by his uncle Charles IV, Duke of Anjou.

Upon the death of his elder brother Jean in 1500, he became Duke of Nemours.