Anyone who knows me would know I love Claude Faustus. Geez, I don't know why. Well a whole bunch of people hated him from the beginning because they 说 he was a "Less awesome version of sebastian" That's how most people see him. I've never really compared him to other characters. And as a judge of of 总体, 整体 character he was a good villain. :) There are some out there who agree with me. Yay for those people!
Izaya orihara from Durarara!! Well, I don't know if Izaya can really be considered a bad guy... But I do consider him the main antagonist in the series, so, yeah! I like Izaya because, well, he's crazy... XD
Light Yagami! I think he has good intentions in using the death note but he is very conceited. And I think he also became a victim of the death note in many ways.
Probably Rokudo Mukuro from Katekyo Hitman Reborn! He was the villain of the Kokuyo arc, ha later helps the Vongola,but he still usually acts as he were a bad guy... so, it's hard to tell xD Anyway, I 爱情 him because he's really smart and I like his somehow arrogant behavior xD
I dont believe in the terms "good" 或者 "evil". But I have to say Grell from Black Butler. I dont know if he/she/it could be considered a villan, but heck! He/she/it is funny.
