Some characters are the best at what they do, but what they do is not very nice.
Other characters are the best at what they do, but they're
not very nice. This trope is about the latter.
It could be anything: cooking, fighting, racecar driving, making music, collecting charity donations, or even dog grooming. Whatever it is, they're one of the best, if not the best person there is in the setting who does it. If it's about knowing something instead of doing something, they're the
person to go to on the subject.
But they are, for lack of a better word, a complete and total Acehole. Perhaps they're a Drama Queen
or are very arrogant. Maybe they rub their skill in everyone's faces, or are obnoxious and reckless. Perhaps they even plan to ahnnihilate the human race in nuclear fire.
In any case, they're superlatively good or knowledgeable when it comes to something, but are unlikable.
They're not necessarily villainous by nature, but don't expect them to be cast as anything more than an Anti-Hero
No Real Life Examples, Please!