@Eliza The first drama I saw from him was also She Was Pretty and I didn't like him either but ever since I started watching Fight For My Way I adore him so much, you gotta watch it ^.^
Kim Soo Hyun, I hate him , his face, his acting, his voice, just a fucking terrible actor, i really don't like him
Suzy
Jang Geun Suk
Jang Na Ra
Hwang Jung Eum
Kim Hyun Joong
Ku Hye-sun
Shin Se Kyung (thought she was alright in SFD though)
Park Shin Hye
Lee Min Ho -  I don't hate him but he is not an actor he is totally over rated, his looks have got him where he is today stick to modelling LMH.
Ryu Hwa Young. Hate her with all my might!
I think Park Shin Hye isn't a good actress but she is everywhere. Same goes for Lee Min Ho
Gong Hyo Jin and Yoo In-Na
@renebean @Asena Yeah, I thing I just saw him in the wrong characters.
I read only good things about FFMW and everyone is loving it. I'll watch it soon.
many people talk about park shin hye now. one question from me is what happened with her nose? hahaha
i see something different lol.
I think Park Shin Hye and Shin Se Kyung improved dramatically from their earlier dramas.  You know who hasn't changed?  Jang Geun Suk

My god he does the same role and the same expressions in every show and movie he is in, and I have no idea why he is popular.

Go Ah Ra is the same to me.....she makes the same pout/pursing of her lips for almost every scenario.  Maybe that's just me.
I haven't liked any of Lee Min Ho's dramas, and I've already watched 3. Maybe drama #4 will be the winner? It's not even like I'm picking the wrong shows. From what I can tell, lots of people loved Boys Over Flowers and City Hunter. Maybe fewer people like The Heirs, but it still seemed pretty popular. He tends to play the same character over and over, and that character is one that I just can't stand. 
Choi Minho and that guy, Kwon Yul .. I also kinda hate Ji Chang Wook and Lee Jong Suk but I still watch their k-dramas.
Uhm, Park Shin Hye? It's not that I hate her. I just really don't like her, and I can't even finish any of her dramas. :(
I can't say I "hate" them since the word is a bit strong but I don't like the way they act their characters and they somehow always have me dislike the show because of that: Shin Se Kyung and Goo Hye Sun. Both for the same reason: weird bland face for all emotions.