One can only defeat so many villains that want to "cover the world in darkness" before one starts to look for a different flavor of horrible.
EVIL JUST GOT EMO!
A society in which people believe that the hundreds of stars that dot the sky are the dreams of the sleeping. When the sun goes down, and the people of the world rest, the dreams begin to seed the sky, disappearing in the morning as the populace awakes once more. It could be just a folk tale, or it could be real...