Ferdinand I (2 June 1424 – 25 January 1494), also known as Ferrante,Also Ferrando, Fernando or Ferdinando. was king of Naples from 1458 to 1494.

Ferdinand I (Spanish: Fernando I; 27 November 1380 – 2 April 1416 in Igualada, Òdena) named Ferdinand of Antequera and also the Just (or the Honest) was king of Aragon, Valencia, Majorca, Sardinia and (nominal) Corsica and king of Sicily, duke (nominal) of Athens and Neopatria, and count of Barcelona, Roussillon and Cerdanya.

Ferdinand I (19 April 1793 – 29 June 1875) was Emperor of Austria from March 1835 until his abdication in December 1848.

Ferdinand I (31 October 1345 – 22 October 1383), sometimes called the Handsome or occasionally the Inconstant, was the King of Portugal from 1367 until his death in 1383.

Ferdinand I (Italian: Ferdinando I; 12 January 1751 – 4 January 1825) was King of the Two Sicilies from 1816 until his death.

Ferdinand I (Ferdinand Maximilian Karl Leopold Maria; 26 February 1861 – 10 September 1948) was Prince of Bulgaria from 1887 to 1908 and Tsar of Bulgaria from 1908 until his abdication in 1918.

Ferdinand I (Ferdinand Viktor Albert Meinrad; 24 August 1865 – 20 July 1927), nicknamed Întregitorul ("the Unifier"), was King of Romania from 1914 until his death in 1927.