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.