Meriwether Lewis Clark Jr. (January 27, 1846 – April 22, 1899) was the founder of the Louisville Jockey Club and the builder of Churchill Downs, where the Kentucky Derby is run.
When his mother died, Clark, called "Lutie" by his family, went to live with his aunt and her sons John and Henry Churchill.
The Churchill brothers were the entrepreneurs providing the financial backing, and Clark was the acting president and on-site manager.
He is reported to have threatened prominent breeder T. G. Moore with a gun, ordering him off the premises after having knocked him down in a dispute over fees.
In addition to building Churchill Downs and originating the Kentucky Derby, he wrote many racing rules that are still in force today.