I have a list of characters I hate in One Piece. Starting from the most hated to least hated.
Blackbeard - Not only is he a coward, but he killed Thatch over a stupid Devil Fruit. Blackbeard has no honor whatsoever and to be honest, his DF power is way overpowered. That it can nullify the DF power of another is complete bs. Also, he can harbor two DF powers simply because his body is different? Where are the other people who have abnormal body structures and can harbor two DF powers? Show me some more of that and make it more believable instead of just coming out on the buck and saying Blackbeard can have two DF powers for no reason other than an abnormally structured body. I hope his death is vicious.
Sakazuku/Akainu - He's a manipulative, evil and corrupt Marine. Garp should have been allowed to kill him for killing Ace. That he makes Fleet Admiral is astounding. Aokiji would had definitely been a better choice as he is more level-headed.
Borsalino/Kizaru - I just hate this man's face.
Enel - The whole 'I am God' bit was completely annoying and that he was willing to wipe out Sky Island just because it was between the moon and One Piece's world was over the top.
Bellamy - A complete a**hat. He deserved his death.
Vivi - An annoying crybaby who thought she could save everyone. The best moment in the anime was when Luffy hit her.
Boa Hancock - With her constant swooning over Luffy, I'm growing quite sick of the generally heartless 'Empress' who would have killed the three Kuja tribeswomen were it not for Luffy.
Arlong - Who should actually be up there, as well as Hancock, because he is a racecist a**hole.
Duval - He's still ugly and to hunt down Sanji over a wanted poster? It wasn't Sanji's fault that his wanted poster was horribly done.
Donquixote Doflamingo - My first thought when I saw him was that 'Is he queer?' He look's like he'd fit in the Okama marvelously. His powers are a bit much too, being able to control a person's body.
Satori, Hotori and Kotori - Their laugh was annoying as hell.
The Tenryuubito - Stuck up, selfish and corrupt things that don't even deserve the breath in their bodies. I hope they're all dead by the end of the series.