Don Carlos Maria Alfonso Marcelo de Borbón-Dos Sicilias y de Borbón-Parma, Infante of Spain, Duke of Calabria (16 January 1938 – 5 October 2015) was, at his death, the last infante of Spain during the reigns of his cousins King Juan Carlos I and King Felipe VI.

Additionally, he was also one of two claimants to the headship of the dynasty which ruled the Kingdom of the Two Sicilies prior to its incorporation into the Kingdom of Italy in 1861, in which capacity he was also the Grand Master of one of the three branches of the Sacred Military Constantinian Order of Saint George.

The second of three children and the only son of Infante Alfonso de Borbón-Dos Sicilias y de Borbón (1901–1964) and Princess Alicia of Bourbon-Parma (1917–2017), he was born during his parents' exile from republican Spain in Lausanne, Switzerland. As the elder son of Prince Carlo of Bourbon-Two Sicilies by Mercedes, Princess of Asturias (1880-1904), the eldest child of Alfonso XII of Spain, Alfonso had been heir presumptive to the Spanish throne between the death in childbirth of his mother and the birth in May 1907 of a son to his mother's brother, King Alfonso XIII. If Mateu Morral’s attempt to assassinate King Alfonso XIII of Spain had succeeded, Infante Alfonso (Infante Carlos’s father) would have become at that moment the King of Spain.

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