Alexander Robert Reinagle (23 April 1756 – 21 September 1809) was an English-born American composer, organist, and theater musician. He should not be confused with his nephew of the same name, Alexander Robert Reinagle (21 August 1799 – 6 April 1877), also a composer and organist, who lived all his life in Britain. He was a close friends with a young Mozart when he visited London. He was influenced by Haydn, Mozart and Clementi.