John Monroe Van Vleck (March 4, 1833 – November 4, 1912) was an American mathematician and astronomer.
He taught astronomy and mathematics at Wesleyan University in Middletown, Connecticut for more than 50 years (1853-1912), and served as acting university president twice.
The Van Vleck Observatory (at Wesleyan University) and the crater Van Vleck on the Moon are named after him.