Altisidora (1810–1825) was a British Thoroughbred racehorse and broodmare best known for winning the classic St Leger Stakes in 1813. Bred, trained and raced in Yorkshire she won two of her three races as a two-year-old in 1812. She was unbeaten for the next two seasons, winning three races including the St Leger at Doncaster as a three-year-old and four as a four-year-old in 1814.