Ο Charles III (Charles III, 1716-1788) was King of Spain from 1759 to 1788 and is considered one of the most important rulers of Spain in the 18th century. He was the son of Philip V and belonged to the Bourbon dynasty. His reign was characterised by important economic, educational and administrative reforms, which helped to reform the state in order to strengthen central authority and develop Spain as a power in Europe. He introduced the European Enlightenment to Spain, espousing the ideas of reason, science and the reform of the state.

As for his involvement in Freemasonry, Charles III was indeed a Freemason and was recognised for his support of the Masonic Brotherhood. He is also known to have been favourable to the Brotherhood and its influence in Spanish society increased during his reign. Charles III is also considered responsible for strengthening the institutions of Freemasonry in Spain, although his personal involvement remained largely discrete.

His reign was marked by Enlightenment reforms and the promotion of intellectual and philosophical movements of the time, including those associated with Freemasonry.

He died in Madrid on 14 December 1788.