Majin Vegeta
He was mentally so strong-willed that he 'allowed' the greatest sorcerer to 'control' his mind and body (at least that's what the sorcerer thought), just for his own personal gain in becoming physically stronger. When it came to the sorcerer trying to use Vegeta's body for his own agenda, Majin Vegeta refused, which had never happened to the sorcerer before, and then he used that enhanced power for his own uses. He's too badass. Overall Vegeta's character has probably had the most development generally throughout the entire series which is why I like him a lot, but Majin Vegeta just demonstrates raw will-power and mind control to a degree which hasn't been shown since from any other character!