Louis Prosper Gachard (12 March 1800 – 24 December 1885), Belgian man of letters, was born in Paris. He entered the administration of the national archives in 1826, and was appointed director-general in 1831, a post which he held for fifty-five years. During this long period he reorganized the service, added to the records by copies taken in other European collections, travelled for purposes of study, and carried on a wide correspondence with other keepers of records, and with historical scholars.