Park Hae Jin, he's completely overrated. 
Kim Young Kwang (no comment...)
Jun Gook Hwan (I love to hate him though, great actor xD)
Choi Jin Ho (evil just evil lol not his fault though haaah)
Jeong Dong-hwan (his one evil role stuck with me forever...xD)

(I don't hate-hate them though as people. except Kim Young Kwang)

Song Joong Gi . I just can't with him 
Jandi actress and the female lead who were playing at "the girl who sees smells"
I really don't feel Hwang Jungeum and Park Shinhye. But seriously, I can still watch Hwang Jungeum with her repeated portrayal of herself in every drama rather than watching Park Shinhye doing absolutely nothing in every show.
I just can't with Aibu Saki... she was the first Japanese Actress I watched in a Japanese Drama... Absolute Boyfriend... she ruined it for me... It became worse when she played the bitchy cheater-ex-girlfriend in Buzzer Beat... :P
male : Lee Seung-gi  
female : the lame Ku Hye‑sun  ... the emotionless, poor actress park shin-hye

i can stand lee sueng-gi if the drama overall is good .... but ku hye-sun  ( known for guem jan-di in boys over flowers ) omg if they pay me to watch her , i still will never watch her .... she makes me wanna kill somebody every time i see her face.
Park Shin Hye
Lee Min Ho

It's not like I hate them.
I just think they are definitely no different than many other actor/actress.
Yet unfortunately they are overrated
Definitely Lee Min Ho... Hate is too strong of a word but I dislike him.


Also there's just something about Lee Sang Yoon and So Ji Sub that makes me avoid their dramas. Again, I wouldn't say I hate them though...
Song Joong-ki
Lee Min Ho
Song Hye-kyo
Sung Joon ... I cant I just hate him so much
Jang Geun Suk
Sung Joon
Jin Seyeon is a lame excuse of an actress for me. She only get roles because she's pretty, since her acting is terrible.
Gong Hyo Jin 
In her early dramas ... she was sooooo whiny and sad ... 
It makes me sad since I avoid good dramas because of her e.g. master's sun, jealousy incarnate, it's okay that's love and the greatest love. what am i missing?