Charles II of Spain, known as "Charles the Bewitched" (Carlos el Hechizado in Spanish), was the last Habsburg ruler of the Spanish Empire. He reigned from 1665 until his death in 1700. Born on November 6, 1661, Charles was the son of King Philip IV of Spain and Mariana of Austria. His reign is often remembered as a period of decline for Spain, a time when the power and influence of the Spanish Empire waned significantly.

Charles II's nickname, "the Bewitched," reflects contemporary beliefs that his physical and mental health issues were due to sorcery. He suffered from numerous health problems throughout his life, which are now believed to be the result of extensive inbreeding within the Habsburg family. His health issues included, but were not limited to, physical disabilities, a weakened immune system, and fertility issues, which led to his failure to produce an heir. His condition was so severe that it significantly impacted his ability to rule effectively.

Charles II's reign was marked by political instability, economic decline, and the loss of territories. His death without a direct heir led to the War of the Spanish Succession (1701–1714), a major European conflict that concluded with the Treaty of Utrecht. The treaty marked the end of the Habsburg rule in Spain, and the beginning of the Bourbon dynasty with Philip V, the grandson of King Louis XIV of France, ascending to the Spanish throne.

Charles II's legacy is often viewed in the context of the decline of the once-mighty Spanish Empire, and his health issues are frequently cited as a stark example of the dangers of dynastic inbreeding.