For some reason, capital-E Evil and most villains just don't get humor. And we don't just mean in a "doesn't understand the joke" sense; they're usually completely humorless or they're cackling because they're complete lunatics and "Eeeeevil!" Maybe it's because of some implicit assumption that "laughter heals the soul", so someone who doesn't laugh or laughs at the wrong things can't be right in the head. Perhaps it's that humor requires perspective, which villains usually don't have in abundance.
The point is, you'll never see a villain who moonlights as a successful stand-up comic in the Muggle world.
This manifests in two different ways.
A complete lack of humor: The villain is either incapable of understanding humor (like an evil Tin Man) or can, but they're so stone-hearted and taciturn that they find nothing funny, never even cracking witty remarks or exchanging repartee with the hero. While there are plenty of stoic Anti Heroes, heroes as a whole can generally laugh at least once in a while. Understandably, they often get placed opposite a wisecracking hero who uses them as an unwitting Straight Man.
An especially sick and twisted sense of humor: Where a "good joke" to them is either not funny to normal people at all, goes way past Black Comedy, or a horrifying torture to the pranked... at times so horrifying that it drives them insane. These villains often have quite a bit of dark wit to them and, if they embrace a "prankster" motif, make cutting and accurate remarks and love irony, may occasionally go all the way to actually being funny, in a very dark sort of way. You can expect these deranged comedians to face especially straitlaced heroes who "never get the joke", say "You're Insane!", and get thanked for it. Often associated with Faux Affably Evil characters.
Contrast Affably Evil. Tension-Cutting Laughter is a subversion. See also No Sense of Humor. Often, this may result in a Laugh with Me! moment.
