Roger I Armagnac (1190 – 22 March 1245) was Viscount of Fezensaguet. He was the son of Bernard I, Viscount of Fezensaguet and Lomagne, and Geralda de Foix.
Roger I of Fezensaguet married Pincelle, the Maid of Albret, daughter of Amanieu IV, Lord of Albret, and Asselide Tartas.
Their children were: