The Top 100 Things I'd Do
If I Ever Became An Evil Overlord

I think that breaks the general spirit of the rule, which is meant to keep you from a karmic death.

Karmic death? 

No matter how evil the villains are, the good guys can't just kill them: heroes are supposed to be better than that. They need to stay pure and noble (or innocent); role models, exemplars of solving their problems without resorting to bloodshed. If they take another person's life, no matter how justified, they will lose their moral edge, but when the villains are just arrested and hauled away by the police, this isn't satisfying. For one, they have a tendency to escape. For another, the mundane workings of the criminal justice system seem woefully inadequate to hold or to punish a really evil villain. We, the viewers, want to see real justice administered, and we don't trust human hands (or at least not ''heroic'' human hands) to administer it.

So, the writers arrange for the villain to die in a manner that is completely their own fault, or, at least, obviously not the hero's. If they die right in the act of attempting to kill the hero, this gives a particularly nice karmic zing. If they attack after being defeated and then spared by the hero, this is one of the rare circumstances where the hero can dispatch the villain personally and still come across as blameless.

Note that this only applies if the villain is clearly human or the setting's equivalent. If they change into some kind of monster, they are no longer protected by this trope: the hero might hesitate to kill another human, but a mutated, horrendous beast is fair game — doubly so when the villain took this form for the sole purpose of murdering the hero. The trope may still apply if the villain's inhuman nature somehow allows him to escape justice at the mortal heroes' hands; in such a case, their doom would come from a completely unexpected quarter, such as previously abused minions finding and shattering the villain's Soul Jar to avenge themselves, without any involvement from the heroes whatsoever (and the minions possibly not even pulling a Heel–Face Turn) and if a Karma Houdini finally becomes the receiving end of this trope, this is Karma Houdini Warranty.

It's more common in Western markets, as a result of heavy censorship and the general reluctance among writers to feature their character (usually in a show with a younger demographic) doing such acts as killing, especially if they're underage. Occasionally known by the older demographic as "getting one's comeuppance." Given that there is a certain charm to Self Disposing Villainy, this trope can show up in works that allow the hero to kill people; it's just that it's much more common for it to show up in situations where the hero has a no-kill policy for one reason or another.

This trope is less common in more cynical works, where the good guys using lethal force is not only more expected but the refusal for a hero to kill comes off as naive at best and irresponsible at worst.

Karmic Death is an example of Death by Irony. Disney Villain Death, The Dog Bites Back and Just Desserts are subtropes. This trope is the opposite of Karmic Jackpot.

Compare Asshole Victim, Hoist by His Own Petard, A Taste of Their Own Medicine and Karmic Butt-Monkey. See also Cruel Mercy. Adaptational Self-Defense usually involves this. The Killer Becomes the Killed is a Crime and Punishment Series variant.

You kill people all the time, so presumably my story isn't from a "Western market"? 

It's not in a market at all, really: there are only four readers. 

Although also, the censorship TVTropes is talking about is different from the kind in Cheliax. Leastwise in my corner of the West, and... eliding present or potential controversies... there's fairly little that it's illegal to write, it's just that some venues or publishers might ask you to get a rating from the Motion Picture Association of America or ESRB, and parents won't let their kids read you if your rating is too high, which limits your audience.

I'm gathering that your country has very low state capacity. I hope you don't die in the fighting when you're conquered by one of your neighbors.

...Was what I said really that funny? 

A little.

The country I'm from has the most powerful conventional military on our planet, but that's hardly relevant to the question, since both of our neighbors have been allies and friends of ours for a hundred years and more. If there was a war it'd be because our head of state went insane and decided to invade one of them.

I do wonder what would happen to you if "Cheryl" died, though. Would she continue directing you from the afterlife? Would that be end of your telepathic connection to the other three?

Is your country so much stronger that there's no chance of your dying in the insane conquest? Well, I guess even if you did, they'd just raise you, you're too strong to be left dead...

My talents may have been exaggerated by the cooperative hand of fate.

What was that?

I'm not in the military and I wouldn't be asked to march on Canada or Mexico.

But talking about real-world wars is depressing me! Can we get back to the Evil Overlord List?

Sure. What's number twenty-nine?

29. I will dress in bright and cheery colors, and so throw my enemies into confusion.

That's most of why I'm wearing green - the infernal reds and blacks in my wardrobe can wait in there until it's safer to take the mask all the way off.

What's number thirty?

30. All bumbling conjurers, clumsy squires, no-talent bards, and cowardly thieves in the land will be preemptively put to death. My foes will surely give up and abandon their quest if they have no source of comic relief.

...I should preemptively kill every incompetent in the land? That would take a lot of murder... I don't think the public would stand for it. 

But I guess the idea is that if you can pull it off, you should, because you only lose your country's incompetents, who are relatively useless unless they have a narrative role to fill, and worse than useless if they do?

I think it's mostly just a joke, and wouldn't help even if you tried. Imagine opening a book that starts with an evil queen deciding to kill all of the talentless but amusing people in the entire land in the fear that one of them would defeat her or contribute to her defeat in some improbable (but amusing) way.

Now flip to the last page. How does that book end?

I take your meaning. What's number thirty-one?

31. All naive, busty tavern wenches in my realm will be replaced with surly, world-weary waitresses who will provide no unexpected reinforcement and/or romantic subplot for the hero or his sidekick.

That's less wasteful than murdering all the nation's incompetents, since it's more targeted and also I could find other uses for the naive, busty tavern wenches. But I infer that this is another joke like number thirty?

That's my read as well.

What's number thirty-two?

32. I will not fly into a rage and kill a messenger who brings me bad news just to illustrate how evil I really am. Good messengers are hard to come by.

Yeah, I've definitely known people like that.

This is solid advice for those who need to hear it.

You've known people, plural, who fly into a rage and kill messengers? Where do you meet them??