What would happen if all the Demon/Devil Lords were killed?

[Sims]

Would the Angel Lords get mad that no one was controlling the evil hordes anymore? Or would the Abyss just fall into.....uh....chaos? (Well it already is that way XD)

[Gensh]

Well, from what I recall, the different kinds of angels passive-aggressively hate each other as much as the different kinds of fiends actively do, so nothing much would happen on that front. As far as the Abyss goes, nothing much would happen; there are an infinite number of demons, and while the bell curve means that we don't ever see more than a few really powerful ones at once, it wouldn't be that long before some new ones popped up. Baator, on the other hand, would be effectively ruined and would likely be conquered by the Abyss unless an evil god decided they wanted to take over, but I doubt most would consider it worth the effort of dealing with the demon hordes. Or the yugoloths would do something, but WotC tends to forget about them, so I don't actually know that much about them.

[Sacrieur]

The Abyss would make more.

[Sims]

Muahha hahahaha!!!!! Splendid! XD After word of me destroying Demogorgon, Molydeus, and Baphomet get out hahaha I'd love to watch the others fear my onslaught! XD

[Eldan]

Molydeus ain't a demon lord. It's a kind of demon that just got a bit neglected in 3.X.

Anyway. The abyss can just make more demon lords. The layers will choose new lords for themselves.

As for the hells... someone will fill the empty spots in the hierarchy. There's too much belief in hell for it to just collapse like that.

Alternatively, the 'loths declare "experiment over" and storm the heavens.

And without much else to do, the Archons would probably declare war on something else. Evil mortals. Or the Slaad, perhaps.