Listed #1 is none other than James Harrison. From USA Today.

James Harrison

Pittsburgh Steelers linebacker James Harrison is probably a nice enough guy off the football field, but when he dons his helmet, you best keep your distance.

HARDEST HIT: On Oct. 17, 2010, Harrison knocked out two Cleveland Browns players in one game. ... ures/G3296

Im not sure if they are in any sort of order, but Bobby Knight is listed as 20th and John McEnroe 19th. Mike Tyson is 13th with Tonya Harding at #5. In the end who cares........