John Marsh (31 May 1752 – 31 October 1828) was an English gentleman, composer, diarist and writer born in Dorking, England.
A lawyer by training, he is known to have written at least 350 compositions, including at least 39 symphonies.
While today known primarily for his music, he also had strong interest in other fields, including astronomy and philosophy, and wrote books about astronomy, music, religion, and geometry.