If you've watched ESPN and their coverage of the NFL you know who John Clayton is. Even if you're not a sports fan, you may know who John Clayton is from his classic "This Is SportsCenter" commercial from around 2012. John was known as the "Professor" because he knew so much about the NFL. The commercial he shot for Sports Center focused on the 'real' John Clayton. A Slayer fan who still lives with his mom. It quickly went viral and is still hailed as one of the best promos that ESPN has ever shot. "The Professor" John Clayton passed away Friday at the age of 67.