Peter IV (Balaguer, Catalonia, September 5, 1319 – Barcelona, Catalonia, January 6, 1387), called el Cerimoniós (Catalan for "the Ceremonious") or el del punyalet (Catalan for "the one of the little dagger"), is the King of Aragon, King of Sardinia and Corsica (as Peter I), King of Valencia (as Peter II), and Count of Barcelona (and the rest of the Principality of Catalonia as Peter III) from 1336 until his death.

He deposes James III of Majorca and makes himself King of Majorca in 1344.

His reign is occupied with attempts to strengthen the crown against the Union of Aragon and other such devices of the nobility, with their near constant revolts, and with foreign wars, in Sardinia, Sicily, the Mezzogiorno, Greece, and the Balearics.

His wars in Greece make him Duke of Athens and Neopatria in 1381.