I will recommend
I saw the devil - Choi min shik is a ****ing psycho and lee byung hun is a total badass hero.
http://mydramalist.com/1063-i-saw-the-devil
The terror live - also great, it is a one room thriller between newscaster( ha jung woo) and a psycho audience who threaten him.
http://mydramalist.com/7240-the-terror-live
The chaser - ha jung woo as psychopath killer
http://mydramalist.com/1538-the-chaser
Confession of murder is very intriguing movie about a criminal that confess his crime after so many years but it is not as simple as that. It come with some actions and thrilling moments
http://mydramalist.com/3907-confession-of-murder
Hide and seek is another great mystery thriller movie, about two families who believe there is strangers that hiding in their home and they struggle to find out the strangerss.
http://mydramalist.com/7393-hide-and-seek
The traffickers is about human organ trafficking in the ship with suspense and intriguing storyline.
http://mydramalist.com/4954-the-traffickers