Balthasar Carlos was a Spanish prince born on November 17, 1629, in Madrid. He was the son of King Philip IV of Spain and Mariana of Austria. Balthasar Carlos was the heir apparent to the Spanish throne, but he faced health issues throughout his life. Tragically, Balthasar Carlos died at a young age on March 5, 1646, at just 16 years old. His untimely death led to a succession crisis, as he was the only surviving son of his parents. After his passing, the Spanish crown passed to his younger sister, Maria Teresa of Spain, who later married Louis XIV of France.