Charles III of Spain
Charles III (Spanish: "Carlos"; Italian: "Carlo"; 20 January 1716 – 14 December 1788) was King of Spain (1759–1788), after ruling Naples as Charles VII and Sicily as Charles V (1734–1759).
He was the fifth son of Philip V of Spain, and the eldest son of Philip's second wife, Elisabeth Farnese.
A proponent of enlightened absolutism, he succeeded to the Spanish throne on 10 August 1759, upon the death of his half-brother Ferdinand VI, who left no heirs.
In 1731, the 15-year-old Charles became the Duke of Parma and Piacenza, as Charles I, following the death of his childless grand-uncle Antonio Farnese.
In 1738 he married Princess Maria Amalia of Saxony, daughter of Augustus III of Poland and an educated, cultured woman who gave birth to 13 children, eight of whom reached adulthood.
Charles and Maria Amalia resided in Naples for 19 years.
As King of Spain, Charles III made far-reaching reforms such as promoting science and university research, facilitating trade and commerce, and modernising agriculture.
He also tried to reduce the influence of the Church and strengthen the Spanish army and navy.
His previous experience as King of Naples and Sicily proved valuable.
He did not achieve complete control over Spain's finances, and was sometimes obliged to borrow to meet expenses, but most of his reforms proved to be successful and his legacy lives on to this day.
Historian Stanley Payne wrote that Charles III "was probably the most successful European ruler of his generation.
He had provided firm, consistent, intelligent leadership.
He had chosen capable ministers...
[his] personal life had won the respect of the people."
Ferdinand I of the Two Sicilies
Ferdinand I (12 January 1751 – 4 January 1825), was the King of the Two Sicilies from 1816, after his restoration following victory in the Napoleonic Wars.
Before that he had been, since 1759, Ferdinand IV of the Kingdom of Naples and Ferdinand III of the Kingdom of Sicily.
He was also King of Gozo.
He was deposed twice from the throne of Naples: once by the revolutionary Parthenopean Republic for six months in 1799 and again by Napoleon Bonaparte in 1805.
Ferdinand was the third son of King Charles VII of Naples and V of Sicily by his wife, Maria Amalia of Saxony.
On 10 August 1759, Charles succeeded his elder brother, Ferdinand VI, becoming King Charles III of Spain, but treaty provisions made him ineligible to hold all three crowns.
On 6 October, he abdicated his Neapolitan and Sicilian titles in favour of his third son, because his eldest son Philip had been excluded from succession due to illnesses and his second son Charles was heir to the Spanish throne.
Ferdinand was the founder of the cadet House of Bourbon-Two Sicilies.
Francis I of the Two Sicilies
Francis I of the Two Sicilies( 19 August 1777 – 8 November 1830) was King of the Two Sicilies from 1825 to 1830 and a member of the Spanish royal family.
Prince Antonio, Count of Lecce
Prince Antonio of the Two Sicilies( 23 September 1816 – 12 January 1843) was a son of Francis I of the Two Sicilies and a brother of Ferdinand II King of the Two Sicilies.
Known by his title of Count of Lecce, he was killed at age 26.
Prince Leopold, Count of Syracuse
Prince Leopold of the Two Sicilies( 22 May 1813, Palermo – 4 December 1860, Pisa) was a prince of the Two Sicilies and was known as the Count of Syracuse.
Prince Gaetan, Count of Girgenti
Prince Gaetan of the Two Sicilies, Count of Girgenti( 12 January 1846, Naples, Two Sicilies – 26 November 1871, Lucerne, Switzerland) was the seventh child of Ferdinand II of the Two Sicilies and his wife Maria Theresa of Austria.
Gaetan was a member of the House of Bourbon- Two Sicilies and consort to Isabella, Princess of Asturias, twice the recognized heir presumptive to the throne of Spain.
Through this union, Gaetan was created an Infante of Spain.
Leopold, Prince of Salerno
Leopoldo Giovanni Giuseppe Michele of Bourbon- Two Sicilies, Prince of Salerno( 2 July 1790, Naples, Kingdom of Naples – 10 March 1851, Naples, Kingdom of the Two Sicilies) was a member of the House of Bourbon- Two Sicilies and a Prince of Bourbon- Two Sicilies.
Lucia Migliaccio
Lucia Migliaccio, Duchess of Floridia( 19 July 1770, in Syracuse, Sicily – 26 April 1826, in Naples) was the second wife of Ferdinand I of the Two Sicilies.
Their marriage was morganatic and Lucia was never a Queen consort.
Prince Ferdinand, Duke of Castro
Prince Ferdinand of Bourbon-Two Sicilies, The Duke of Castro
(Ferdinando Maria Andrea Alfonso Marcus; 28 May 1926 – 20 March 2008) was a claimant to the headship of the former Royal House of the Two Sicilies.
Prince Alfonso, Count of Caserta
Prince" Alfonso", Count of Caserta( 28 March 1841 – 26 May 1934) was the third son of Ferdinand II of the Two Sicilies and Archduchess Maria Theresa of Austria.
He was pretender to the throne of the Two Sicilies in succession of his older half- brother, Francis II of the Two Sicilies.
He was succeeded by his eldest son, Ferdinand Pius.

Question: Who is Ferdinand I Of The Two Sicilies's paternal grandfather?
Answer: Philip V