Although Canon doesn't seem to have much information about the background of Zero in the Kirby series, there is a Fanon theory which basically says that Zero is this trope. It is speculated that Zero wants to destroy Dream Land because it is unable to feel positive emotion and envies anyone who has them, so it wants all inhabitants of Dream Land (or the whole Kirby universe) to feel as bad as itself. It tries to reach its goal by destroying the source(s) of all others' positive emotions.
So far this seems to be a pure Fanon theory. (Canon hasn't even confirmed any connection between Zero and Zero 2, although it is commonly thought that Zero 2 is a revived form of Zero.) So does it belong on this page?