Let's recommend true thrillers to one another!

What thriller/suspense/crime/mystery dramas are very much worth the precious time? :)

when read title, i mistake 'dramas' to 'dreams' i thought u wanted to share horror nightmares because i get that a lot HAHAh  thriller drama i recommend VOICE 
I a bit rubbish with thriller type dramas so the ones ive seen are mild.

Cruel City, Love me if you dare and Le Jun Kai
Ouroboros (SO INTENSE) it's Japanese but it's really good. 
I haven't seen that many myself, but of the ones I know of...

Signal
Tunnel
Healer
Voice
Defendant
Sister is Alive
Empress Ki

All these are reasons to loose sleep. I wrote about the last two on my blog. www.dramaunnie.com check it out if you're curious. 

Sister is Alive is a really good drama. I'm so happy every saturday when the two episodes are released
Can we add Circle to this list? That drama is amazing :)