Fyldener (1803–1829) was a British Thoroughbred racehorse and sire best known for winning the classic St Leger Stakes in 1806. In a racing career which lasted from June 1806 until June 1809 he won six times from ten competitive starts. As a three-year-old, Fyldener won his first four races, culminating with a win in the St Leger at Doncaster Racecourse.