Thaddeus John Kwalick is an American former professional football player who was a tight end in the National Football League (NFL) and World Football League (WFL). He played for the San Francisco 49ers from 1969 to 1974 and the Oakland Raiders from 1975 to 1977. In 1975, he also played with the Philadelphia Bell of the World Football League. He was an All-Pro once, three times selected to the Pro Bowl, was All-American at Penn State, and was inducted into the College Football Hall of Fame in 1989.