Ferdinand III may refer to:

• Ferdinand III of Castile, the Saint (1199-1252, king from 1217)
• Ferdinand III of Naples the Catholic (1452-1516, king from 1504) (Ferdinand V of Castile and Ferdinand II of Aragon and of Sicily), husband of Isabella of Castile
• Ferdinand III, Holy Roman Emperor (1608-1657, emperor from 1637)
• Ferdinand III of Sicily (1751-1825, king 1759-1816) (= Ferdinand IV of Naples 1759-1799; 1799-1806; 1815-1816)
• Ferdinand III of Tuscany (1769-1824, grand-duke 1791-1799 and 1814-1824)

This disambiguation page lists articles associated with the same personal name. If an article link led you here, you may wish to change the link to point directly to the intended article.