Duke of Calabria was the traditional title of the heir apparent of the Kingdom of Naples after the accession of Robert of Naples. It was also adopted by the heads of certain Houses that had once claimed the Kingdom of Naples in lieu of the royal title.
There are at present two claimants to the title of Duke of Calabria. In the Spanish context, it is the title for the head of the House of Bourbon-Two Sicilies, and in the Italian context it is the title for the heir to the Duke of Castro, the head of the Royal House.
bef. 1297–1309: Robert, son of Charles II1309–1328: Charles, son of Robert1333–1343: Joanna, daughter of Charles, jointly with her husband Andrew of Hungary1343-1345: Andrew of Hungary, as husband of Queen Joanna I1345-1348: Charles Martel, son of Andrew and Joanna I1381–1382 Louis I of Naples1382–1384 Louis II of Naples1403–1417 Louis III of Naples1432–1434 Louis III of Naples1434–1435 René I of Naples1435–1470 John II, Duke of Lorraine1470–1473 Nicholas I, Duke of Lorraine1473–1481 Charles IV, Duke of Anjou1481–1493 René II, Duke of Lorraine1493–1544 Antoine, Duke of Lorraine1544–1545 Francis I, Duke of Lorraine1545–1608 Charles III, Duke of Lorraine1608–1624 Henry II, Duke of Lorraine1624 Francis II, Duke of Lorraine1624–1634 Charles IV, Duke of Lorraine1634–1661 Nicholas II, Duke of Lorraine1661–1675 Charles IV, Duke of Lorraine1675–1690 Charles V, Duke of Lorraine1690–1729 Leopold, Duke of Lorraine1729–1765 Francis I, Holy Roman Emperor1765–1790 Joseph II, Holy Roman Emperor1790–1804 Leopold II, Holy Roman Emperor1458-1494 Alfonso II of Naples1494–1550 Ferdinand of Aragón1501–1504 Ferdinand II of AragonAs royal title for the heir apparent to the throne:
1747–1777 Infante Felipe (or Philip) (excluded from succession due to mental illness)1777-1778 Prince Carlo (died as an infant in 1778)1816-1825 Francis I of the Two Sicilies (title dropped on accession to the throne)1810-1830 Ferdinand II of the Two Sicilies (title dropped on accession to the throne)1830-1859 Francis II of the Two Sicilies (title dropped on accession to the throne)1894-1934 Prince Alfonso, Count of Caserta (he never used the title)As customary title of the head of the House:
1934-1960 Prince Ferdinando PiusAs customary title of the claimant to the headship of the House:
1960-1964 Infante Alfonso1964-2015 Infante Carlos2015-present Prince PedroAs customary title for the heir of the claimant to the headship of the House:
1973–2008 Prince Carlo (title dropped on succeeding his father as claimant to the headship)2016-present Princess Maria Carolina of Bourbon 
