Plenipotentiary (1831–1854) was a British Thoroughbred racehorse and sire. In a career that lasted from April 1834 to April 1835 he ran seven times and won six races. His most important win came in May 1834 when he won The Derby. His only defeat, in the St Leger at Doncaster later that year, was widely believed to be the result of foul play. After three successes as a four-year-old in 1835 he was retired to stud where his record was disappointing. Plenipotentiary was regarded by racing experts as one of the best British racehorses of his era.

The Derby Stakes, also known as the Derby or the Epsom Derby, is a Group 1 flat horse race in England open to three-year-old colts and fillies. It is run at Epsom Downs Racecourse in Surrey on the first Saturday of June each year, over a distance of one mile, four furlongs and 10 yards, or about 1½ miles. It was first run in 1780.