Antipope Benedict XIII, born Pedro Martínez de Luna, (b. Illueca , Aragon, 1328; d. Penyiscola , near Valencia and Barcelona, c. 1423) an Aragonese, he was a supporter of Robert of Geneva and was elected by the French cardinals on the death of Clement VII Sept. 28 1394. On the death of Urban VI in 1389 the Italian cardinals had chosen Boniface IX; the election of Benedict therefore perpetuated the Papal Schism. The greater portion of the church refused to recognize him, and in 1397 the French church, which had supported him, withdrew from allegiance to both popes, and in 1398 Benedict was imprisoned in his own palace at Avignon. The Council of Constance brought this state of matters to an end and Benedict XIII fled to Penyiscola, a coastal town in the northern border of the Kingdom of Valencia . Benedict abdicated in 1417, having refused to recognise the election of Pope Martin V, but was recognised by Scotland, Castile, Navarre and Aragon until his death in 1424.

He should not be confused with Pope Benedict XIII, who reigned in the 18th century.

The castle in Penyiscola where he lived until his death was restored, improved and new walls where added in 1960 when Anthony Mann's film El Cid was partially filmed there. The town and castle of Penyiscola were playing the role of Valencia.