Undertaker
Apart from being called McMahon’s greatest creation, Undertaker also gets the lion’s share of attacking McMahon apart from Austin. After him and Kane are unable to prevent McMahon from getting attacked by The Rattlesnake, McMahon backtracked on his promise to hand over the WWF Title to either Kane or Undertaker.
He then booked a singles match between them for the next PPV where Austin stands in their way as the special guest referee and then books them in a handicap match for later that night.
All of that did not get him mauled but then Taker caught him flipping him off and that was the END of McMahon. Taker dragged him to the ground, landed furious punches and then both brothers went on to (kayfabe) break his leg.