The Fountain of Youth........ how soon can you sail?
~ Ferdinand asking the Spaniard to locate the Fountain of Youth.
Ferdinand VI of Spain or (King Ferdinand) is a minor yet pivotal antagonist in the 2011 Pirates of the Caribbean film Pirates of the Caribbean: On Stranger Tides. He is the King of Spain and the master of The Spaniard.
Ferdinand first appeared in his palace, where an old sailor rushed in and claimed to have sailed with a deceased Conquistador named Ponce de León, who was searching for the legendary Fountain of Youth located in the Carribean Sea. At first, Ferdinand finds this to be quite ridiculous as he doesn't believe in the legend, but the old sailor presented him the logbook of Ponce's old ship (known as the Santiago), where an archaic symbol in one of its pages is shown as proof of the fountain's existence.
Realizing now that the legend of the Fountain does exist, Ferdinand decides to send in the Spaniard to lead a loyal crew to find the Fountain at all costs. Eventually, King George ll of Great Britain hears upon Ferdinand's intent to locate the Fountain, as well as Blackbeard's intent to use the Fountain to achieve immortal life, so he decided to arrange an expedition for the British Royal Navy to find the Fountain by appointing Hector Barbossa.
However, it's later revealed that Ferdinand has no intention in using the Fountain to achieve immortal life, but rather to destroy the Fountain, as Ferdinand (being a devout Catholic) believes that the Fountain was an affront to God's will and sought to have it destroyed as a testament to God's power. Eventually, in the end, the Spainard and his forces manage to locate the Fountain after overwhelming Blackbeard's crew and the British forces, and they finally manage to destroy the Fountain. With their mission accomplished, the Spainard and his men returned back to Spain to report their success to a satisfied Ferdinand. It is unknown what has happened to him afterwards, but it is likely that he congratulated The Spaniard and his crew for destroying the Fountain and continued to rule until his historical death in 1759.
King Ferdinand is one of the two historical monarchs (the other is King George) to appear in the Pirates of the Caribbean film series. However, unlike King George, Ferdinand has no intention in expanding his empire by any means necessary.
It may be possible that King Ferdinand was the former commander of Armando Salazar and his crew during their voyages of exterminating many pirates prior to the events of the fifth film Pirates of the Caribbean: Dead Men Tell No Tales. However, as the flashbacks take place in the 1710s and the real Ferdinand ascended to the throne in 1746 (four years before the events of Pirates of the Caribbean: On Stranger Tides), it can be assumed that the Spanish King who ruled during Salazar's pirate-hunting campaign was one of his predecessors, most likely Phillip V of Spain.
King Ferdinand may not be considered a villain after all; he was just a devoted Christian monarch who believed in the Church and considered the Fountain of Youth an abomination for granting eternal life to the body rather than the soul as it contradicted the Bible, thus just confused as the Fountain had no connections to the Christian culture. However, by letting The Spaniard to do whatever he has to do to ensure the Fountain's destruction, even shooting Lieutenant Groves, King Ferdinand at the fullest can be considered an Anti-Villain.