Jean-Louis Castilhon (1721, Toulouse – 24 August 1798, Bouillon) was an 18th-century French man of letters and encyclopedist. The brother of journalist and writer Jean Castilhon, Jean-Louis Castilhon was a prolific author who contributed to a large number of periodicals, including the Journal de jurisprudence of which he was the director. He married Philippine Lembert in Bouillon on October 3rd 1766. He gave the Supplément à l'Encyclopédie about 400 articles devoted to History.