William Lowe Waller Sr. was an American politician and attorney. A Democrat, Waller served as the 56th governor of Mississippi from 1972 to 1976. Born near Oxford, Mississippi to a farming family, Waller went to law school and in 1950 established a law practice in Jackson. Nine years later, he was elected District Attorney of Hinds County, Mississippi. Waller attempted to reform the position and provoked the ire of local law enforcement for aggressively prosecuting several cases. In 1964, he twice prosecuted Byron De La Beckwith for the murder of civil rights activist Medgar Evers, with both trials resulting in deadlocked juries. In 1967, he launched an unsuccessful campaign for governor, finishing fifth in the Democratic primary.

Medgar Wiley Evers was an American civil rights activist and the NAACP's first field secretary in Mississippi. He was assassinated by Byron De La Beckwith.