Peyton Manning's nickname is "The Sheriff" because of the way he conducts and directs himself during the pre-snap period before he throws the football. Peyton's less popular nickname is "Auto," which refers to his high skill level and the fact that his football completions are considered automatic.
Peyton Manning's primary nickname, The Sheriff, comes from the fact that when he speaks, everyone listens. He's often heard shouting directions and gesturing even after the huddle has dissolved and his players are at the line of scrimmage. As of 2014, he is considered to be one of the greatest quarterbacks of all time and has attended 13 Pro Bowls.