Majin Vegeta.
Vegeta took this form, when he allowed himself to be controlled by the wizard babidi. With this new form, came newfound power. It also influenced Vegeta to regress to the persona of his past, brutal self. In this form, the majin seal also appears on his forehead. Shortly after obtaining this form, Vegeta requested to have his desired rematch with Goku. Goku and himself, fought each other in both of their super saiyan 2 forms. Their power overall proved to be equal. Goku, after sensing the awesome power of Majin Buu calls an end to the fight. Vegeta then proceeds to knock Goku out, in order so that he may face Buu alone.
Vegeta before making the ultimate sacrifice.
After getting pummeled by Buu, Vegeta decides to make the ultimate sacrifice so that his family and friends may live in peace. Although to no avail, Vegeta's attempt to rid the world of Buu is unsuccessful.