Emergency crews arrived at Butkus’ home in Malibu around 12.51pm, where he was pronounced dead at the scene.Butkus was found unresponsive by a friend who went to check on him, reported TMZ.
Often touted as one of the greatest linebackers of all time, Butkus was one of the most intimidating players to ever step on a football field.
Standing at 6-foot-3 and weighing 245 pounds, he was a standout at the University of Illinois before joining the Chicago Bears in 1965 as the No. 3 overall pick in the NFL Draft.
His entire NFL career was with the Bears from 1965 to 1973.
Throughout his impressive career, Butkus won six All-NFL selections, two Defensive Player of the Year honors and eight Pro Bowls.
He was considered to be one of the most intimidating players to take to the field, and earned several nicknames for his style of play, including The Maestro of Mayhem, The Enforcer, The Animal and The Robot of Destruction.