Frederick Robert Williamson, nicknamed "The Hammer" (born March 5, 1938) is an American actor and former professional American football defensive back who played mainly in the American Football League during the 1960s. He has black belts in Kenpo, Shotokan Karate, and Tae-Kwon-Do. Since 1997 Williamson has had a home in Palm Springs, California.
After playing college football for Northwestern in the late 1950s, he was signed as an undrafted free agent by the Pittsburgh Steelers. When during training camp he was switched to their defense, his attitude over the switch prompted him to play his position with too much aggression, and the coach of the 49ers asked him to quit "hammering" his players. Thus, "The Hammer" quickly stuck and became his nickname.
Williamson played one year for the Steelers in the National Football League in 1960. Next, he moved to the new American Football League. Williamson played four seasons for the AFL's Oakland Raiders, making the AFL All-Star team in 1961, 1962, and 1963. He also played three seasons for the AFL's Kansas City Chiefs.