mostly the dramas where the guy treats the girl badly at first but then he breaks and they end up together so 
Leh Ratree-thai
someone like you-he treated her terribly but you realise he's really vulnerable and hurt all along
also jet chao in when isee you again cause ugh he's incredibly good looking you cant hate him
Shin Sung Rok -- Liar Game && You who came from the Stars
 I was blown away by his acting. Every bit of him is evil' his grin, smirk, poker face and even his laugh and smile. 10/10


Unfortunately I could not pick only one, so I will rank my top three Bad Character. I just love this characters.

1. Zheng Er,
2. Gao We &
3. Yu Wen Yong
All three are in "Prince of Lan Ling"

Plus I must include
Qian Tian Shuang Yi from "Cruel Romance" Thumbs up
Jamie from Liarr Game, such a great whishy washy character that still manages to have some redeeming quailities.
skylord from Warrior Baek Domg Soo, the most charismatic villain I've ever come across.
The villain from 'The Girl Who Sees Scents'. (The only thing I liked in this drama)
My current favorite bad characters are from the same drama.
Gil Tae Mi and Yoo Bang Won from the drama, Six Flying Dragons.  Gil Tae Mi started and ended as a bad character. But Yoo Bang Won is an antihero. He started out good, but turned into a kiss ass bad guy.


sixdragons9-00497.jpg
Without thinking.. it's Mishil of Queen Seon-Deok ♥
The best 'bad' character ever, and I don't think someone who've watched this drama will think otherwise!
Nam Gyu Man from Remember - war of the son