When thinking about a villain, most will think of a maniacal figure lurking in the shadows hellbent on destruction and devastation. In sports, the term is a little broader.
It is reserved both for athletes and coaches who have authored devastation and heartbreak for a fan base: Think Eli Manning for the New England Patriots. It also can be someone whose mere presence and personality makes your skin crawl: Think Floyd Mayweather (boxing skills aside) for most sane people.
Some athletes are born to be the villain. Some have it thrust upon them. For others, their achievements and greatness transform them into the villain, with that role serving as new-found motivation to desecrate their opponents.