Nightmare

ナイトメア

In the series, he serves as the CEO of his own firm, Nightmare Enterprises, which he uses to extend his super evil influence across the universe. He conquers planets by creating and selling monsters through the company.
He makes few appearances in the show itself, showing up only occasionally as a shadowy figure in a handful of episodes, with his full appearance reserved for the finale.
Although he is an intimidating and bloodthirsty warlord, he could also be described as childish. He toys with the citizens of Dreamland; despite having the ability to send planet-destroying threats, he opts to send monsters that range from "a mild inconvenience" to "causes property damage," only completely destroying the town during the finale.
He also uses a chessboard to play out events. In a scene where something goes awry, he destroys the board in a fit of anger.
Nightmare is also very cocky, assuming that Kirby would be unable to beat him in his own realm. He was wrong. Get this man some friends for real.