Akainu

akainu is one the marines admirals and he's the most powerful he ate the magma-magma fruit making him become living magma he's cold and heartless he will kill anyone that he thinks they evil he will also kill his own comrades who run away from battle he will kill they no matter how they beg for merc

he's the one who kill luffy's brother his magma over power ace's fire he even try to kill coby but shank save him akainu is one of the worst villains in one piece