Peter of Aragon (Catalan: Pere d'Aragó, Spanish: Pedro de Aragón; 1305 – 4 November 1381) was an infante (royal prince) of the Crown of Aragon who served three successive kings as a soldier, diplomat and counsellor before joining the Franciscans in 1358.
Peter was the Count of Ribagorza (1322–1358), Count of Empúries (1325–1341) and Count of Prades (1341–1358). He was the most important counsellor of Alfonso IV and Peter IV, and was regent during the absence of the latter (1354–1356). He took part in most of the major military conflicts of their reigns down to his death.
Peter was also an author and patron of letters. As a Franciscan, he advocated an end to the Avignon Papacy and wrote a prophetic tract to that effect.