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. On the board, he represents the Roberts District and once served as chairman of the board, a rotating position. McGlennon is a native of New York, but has lived in the Commonwealth of Virginia since the 1970s.