William Arthur Belk (born February 19, 1946) is a former American football defensive lineman in the National Football League (NFL). He was drafted by the San Francisco 49ers in the 6th round of the 1968 NFL/AFL draft. He played college football at Maryland Eastern Shore. He played for the Toronto Argonauts in the Canadian Football League in 1975 and 1976. He played a total of 9 years of professional football.

Belk was inducted into the University of Maryland Eastern-Shore Hall of Fame in 1984. His collegiate career spanned from 1964 to 1968. In college, Belk was a two-way starter at offensive and defensive end. He received All-Conference honors in 1966 and 1967, and was co-captain of the team his senior year. While in college, Belk was a student athlete, making the honor roll and dean’s list. He graduated in 1968, earning a bachelor's degree in Business Education.

In the NFL, Belk proved to be a versatile, reliable, and very intelligent football player, starting at both defensive end and tackle. One of his coaches, Dick Nolan, made this testimony in reference to Belk, “What I like about Bill is that he's very smart. He knows exactly what he's doing out there and can adjust to any situation."