Roger IV (died 24 February 1265), son and successor of Roger-Bernard II the Great, was the eighth count of Foix from 1241 to his death. His mother was Ermessenda de CastellbĂČ. His reign began with the south again at war with the north in France and, though he was reluctant to join his father's old ally, Raymond VII of Toulouse, in revolt and he did not aid the king of England, Henry III, in his Saintonge War.
Roger IV was a vassal of both the count of Toulouse (for his county of Foix) and the king of France (for his Carcassonne lands), then Louis IX. His loyalty to the king, however, took precedence and war broke out with Raymond VII (October 1242). Although Raymond was forced to submit to the king on 30 November, the war with Roger continued until January 1243, when the king ended it. The count of Foix was now solely a vassal of the king and Raymond spent the rest of his life (until 1249) trying to retrieve Roger's homage, to no avail.