Sakazuki formerly known as Akainu is one of the two main antagonists of One Piece (alongside Blackbeard also known as Marshall D. Teach). He is notable for murdering Monkey D. Luffy's adoptive brother Portgas D. Ace, making him Luffy's marine arch-nemesis. He is the main antagonist of Marineford Arc and the remainder of the series.
To make matters worse, he literally KILLED HIS OWN SOLDIERS! One example includes almost killing Koby just because he was distraught over his fellow soldiers dying and wanted the war to end. And he would be dead if it wasn't for Shanks saving his life.
He also killed a soldier running away from battle just because he wanted to see his family again.
When Blackbeard and his pirates arrived and destroyed Marineford, he did not help Sengoku battle them.
He claims that he is a hero, when he is instead a big villain since he bullies and kills pirates a lot.
He mocks Whitebeard in front of his adopted son, Ace, causing Ace to retaliate in anger and leading to his death.
He is notable for killing Ace and shows no remorse for that, even preparing to punch him again after he's fatally wounded Ace. This caused Luffy to have a mental breakdown, even after the Marineford War.
He was about to kill Luffy when he was rendered comatose and defenseless which just showed he doesn't care if one is defenseless or not, even if that one is a pirate.
Speaking of Luffy, he is responsible for his chest scar as well.
He made Squard, a fellow pirate of Whitebeard, stab his own captain.
Even when he's angry at the Five Elders for helping Doflamingo falsely announce his resignation from the Seven Warlords, he really only cares about how it would affect his reputation instead of the morality of helping someone like Doflamingo.
Even though he supposedly wants to preserve justice, he cares more about preserving his image and ideals of justice than actually helping people. This is proven when he yelled at Fujitora for revealing Luffy and Law defeated Doflamingo and also publicly apologizing for the World Government's involvement in allowing Doflamingo to rule Dressrosa, since it was admitting responsibility for something the World Government did wrong.
He ordered the Marine bases to turn Fujitora away just because he did not kill Luffy and Law.
The ONLY Redeeming Quality
It was very satisfying watching Akainu get his butt handed to him on a silver platter by Whitebeard after killing Ace and he got what he deserved by the man the Whitebeard Pirates called "Pops."
His appearance is based on the Japanese actor, Bunta Sugawara.
His favorite foods are rice and red pepper.
According to the creator of One Piece, Eichiro Oda, he was so powerful that he could end his One Piece manga in a year.