Joker


 * Intelligent: He matches actual geniuses like Batman through sheer incredible cunning and strategy alone, and is amazing at planning ahead and twisting all odds into his favor.
 * Psychotic: The Joker is a sadistic lunatic who will murder anyone on a whim, even his own men.
 * Spiteful: The Joker goes out of his way to push the buttons of Batman and his fellow criminals any way he can merely for amusement, and has no standards when telling dark or insulting jokes at others' expenses. The best examples are the incarnations where he finds out Batman's true identity, and brutually taunts him over his parents' traumatizing murder nonstop.
 * Sadistic: He sees viciously psychologically and physically abusing his "girlfriend" Harley Quinn as a fun hobby. He also gruesomely tortures innocent people to death when he's bored.
 * Chaotic Evil: The Joker is simply chaos personified, and, as Alfred puts perfectly, "Some men just want to watch the world burn."
 * Fearless: As a nihilist, when the Joker is getting brutally pounded half to death by an enraged Batman or is dropped off a building to his apparent death, all he can do is insanely cackle.
 * Hammy: The Joker is a very loud and theatrical villain, best personified by his over-the-top clown motif. He revels in the showiness and attention being a borderline-terrorist comes with. Whenever he does decide to seriously attempt Batman's murder, he makes sure to make it a work of art.
 * Haughty: The Joker, as a sociopath, is so egotistical that his Tim Burton incarnation wants is "[his] face on the dollar bill". He also can't stop looking at himself in the mirror, favoring his own face over the bodies of his extremely attractive mistresseses.
 * Sociopathic: The Joker deeply understands morality and the structure of society, but dedicates his life to demolishing it any way he can, no matter how many lives he claims or destroys. He can also be incredibly charming, as he turns Harley Quinn, a former respected and civil psychologist, into the religiously dedicated lunatic she is today with mere words alone.