Personally, I like DaiGunsō (or Dark Keroro) from “Keroro Gunsō Super Movie 3: Keroro vs Keroro Great Sky Duel, de arimasu!”
He is my favorite anime-movie antagonist because of the way he presents himself. He is very smart, cunning, and driven to complete his tasks, albeit a little childish as well. He is an all-around better clone of Keroro, the main protagonist of the film.
He is the commander of a powerful space ship called “The Sky City,” that him and his 3 followers alone control. He managed to take over earth in two minutes thanks to his outstanding tactics that allowed him to come up with a nearly flawless invasion plan.