Richard Marvin Butkus (born December 9, 1942) is an American former professional football player, sports commentator, and actor. He played football as a middle linebacker for the Chicago Bears of the National Football League (NFL) from 1965 to 1973. He was invited to eight Pro Bowls, named a first-team All-Pro six times, and was twice recognized by his peers as the NFL's Defensive Player of the Year. He was renowned as a fierce tackler and for the relentless effort with which he played and is widely regarded as one of the greatest and most intimidating linebackers in pro football history.

Butkus was born in Chicago and played his entire football career in his home state of Illinois, which began at Chicago Vocational High School. He was a linebacker and a center at the University of Illinois. He was a two-time consensus All-American, and he led the Illini to a Rose Bowl victory in 1963 and was deemed the most valuable player in the Big Ten Conference. He was named college football's Lineman of the Year in 1964 by United Press International (UPI). He was inducted into the College Football Hall of Fame in 1983.

Butkus was drafted by the Bears as the third overall pick in the 1965 NFL Draft. He soon established himself as a ball hawk with his penchant for forcing turnovers. In his NFL career, he intercepted 22 passes and recovered 27 fumbles (a record when he retired), and he was responsible for causing many more fumbles with his jarring tackles. His tackling ability earned him both admiration and trepidation from opposing players. According to Hall of Fame defensive end Deacon Jones, Butkus "was a well-conditioned animal, and every time he hit you, he tried to put you in the cemetery, not the hospital." In 2009, the NFL Network named Butkus the most feared tackler of all time.

Butkus is credited with having defined the middle linebacker position, and is still viewed as the "gold standard by which other middle linebackers are measured." He was inducted into the Pro Football Hall of Fame in 1979, and his No. 51 jersey is retired by the Bears. Following his playing career, Butkus began careers in acting, sports commentary, and celebrity endorsement. He is active in philanthropy through the Butkus Foundation, which manages various charitable causes.