John J. McGlennon (born July 23, 1949) is an American politician of the Democratic Party, a professor at the College of William and Mary, and a member of the Board of Supervisors of James City County, Virginia.
McGlennon has been with the College of William and Mary since 1974 and served as the chairman of the Government Department from 1993 to 2003.
He has many publications to his credit, including two books: The Life of the Parties: A Study of Presidential Activists, with Alan Abramowitz and Ronald Rapoport and Party Activists in Virginia, also with Alan Abramowitz and Ronald Rapoport.
McGlennon ran for the United States Congress as a Democrat in 1982, almost defeating the Republican candidate in the open seat, Herbert Bateman, in a year that was bad for the Republican Party nationally.
In 1997 he was elected to the James City County Board of Supervisors and has been re-elected 6 times.