John IV (15 October 1396 – 5 November 1450) was a Count of Armagnac, Fézensac, and Rodez from 1418 to 1450. He was the son of Bernard VII of Armagnac, Count d' Armagnac, of Fézensac, Pardiac, and Rodez; and the brother of Bernard of Armagnac, Count of Pardiac, of La Marche and Duke of Nemours.