Carlos, Prince of Asturias

Don Carlos, Prince of Asturias, was the eldest son and heir apparent of King Philip II of Spain. His mother was Maria Manuela of Portugal, daughter of John III of Portugal. Carlos was known to be mentally unstable and was imprisoned by his father in early 1568, dying after half a year of solitary confinement. His imprisonment and death were utilized in Spain's Black Legend. His life inspired the play Don Carlos by Friedrich Schiller and the opera Don Carlos by Giuseppe Verdi.