Obviously has to be David Busst, or that Danish player who's kneecap popped half way up his thigh during Euro 92, leaving an attractive lump poking through the skin.
This challenge by Germany Keeper Harald Schumacher left French player Cedric Battiston unconscious and minus his front teeth. The German didn't even get booked!
There is a video clip somewhere of 2 kickboxers going at it. 1 of them kicks out to the others thigh and his whole shin just folds. He hobbles round for a bit with it just hanging off like a bit of meat. Everytime I think I feel rough