William N. Grover (July 17, 1817 – August 25, 1899) was an American judge and United States Attorney for the eastern district of Missouri.
He was one of five defendants tried and acquitted in Illinois for the murder in 1844 of Joseph Smith, founder of the Latter Day Saint movement.
As a captain in command of the Warsaw Cadets in the Illinois militia, Grover was accused of having ordered his men to storm the jail and attack the Smiths.
Grover had been a leader of the Anti-Mormon Party in Hancock County.
In 1863 he was appointed as a United States Attorney for the eastern district of Missouri.