Final answer:
King Carlos III of Spain called for the establishment of an Academy of Spanish in Mexico City, which became known as the Academy of San Carlos.
Step-by-step explanation:
The individual who called for the establishment of an Academy of Spanish in Mexico City, that eventually became known as the Academy of San Carlos, was King Carlos III of Spain. The academy became fully functional in 1785 with Jeronimo Antonio Gil appointed as the first director. This request was part of a broader effort to spread education and culture in the New World, alongside the religious education provided by missionaries and secular clergy who taught Christianity to the local populations.