Kabuto. Hopefully before the series even started. He's more psychopathic than Julius Caesar. Like, God, man. Take a chill pill.
Hanzo and Danzo, if they weren't already dead. I blame them for almost everything bad that happened in the series. If you trace it back far enough, it all leads to them.
The Akatsuki lackies who let themselves succumb to mind-control.
Kinda wanna kill the Third for telling Orochimaru that his parents will come back.... (Before he tells Little Oro that, obvs) Other than H&D, he's the only villian in the series.
Oh, and Fugaku. He's a big villian, too.
EDIT: And those dickbags who kidnapped Sakumo's teammates. If he didn't have to save them he could've stopped whatever Shinobi World War was going on at the time (I want to say Second?) in it's tracks, preventing Hanzo from invading Amegakura and blahdee blah blah.
I would really kill the Raikage (Killer Bee's Brother), I really detest him. I would also kill Sakura because she wanted Naruto to go after Sasuke and now she just wants him to forget Sasuke. I would also kill Karin she seems utterly useless in the show. Kabuto really needs to die because of the kiss up act Kabuto showed to Orichimaru which really pissed me off.Most definitely kill Sasuke that selfish ***** who just needs to realize his actions, going all power hungry just 'cause he has Sharingan which makes him seem all high and mighty.