Answer
Greene retired from the NFL in 1981 after a successful career spanning 13 seasons. He played for the Pittsburgh Steelers, Washington Redskins, and San Francisco 49ers, earning four Super Bowl rings and establishing himself as one of the greatest linebackers in NFL history. Greene's retirement marked the end of an era for the Steelers' "Steel Curtain" defense, which had dominated the NFL in the 1970s.