Dragon Ball characters who start out as villains have a habit of not staying that way. Several arcs of the original anime, ...

That means that Majin Kuu, unlike most forms of Majin Buu, is an intelligent villain in Dragon Ball, which immediately sets the characters apart, despite functionally being the same type of creature.

The original Dragon Ball Editors talks about incorporating an iconic character in the Majin Buu Saga to help lift Akira Toriyama's spirits.

Dragon Ball Daima's ending confirmed the new Demon King after a long battle, and the answer will surprise you.

This is something that a few characters in the Buu saga went through ... to one of the most popular moments in anime since Majin Vegeta is a very beloved arc in that character's history.