Actors who have impressed me and where

I cannot pick his best acting job, because each and every one of his performances was stellar and flawless. He doesn't have to talk to express a myriad of emotions yet he can crush me with a broken smile or a subtle change in his body language. This actor can play any character with unbelievable skill and he has never, ever disappointed me, hence why he's my top favourite.

He completely blew me away in Duel (main) and enchanted me in My Country. His acting is so subdued, so realistic, so full of vulnerability, he wins my heart in seconds. Wow, this man can act.

In Tale of the Nine Tailed Fox (main). How could I resist my favourite type of character: the broken villain? He commits horrible things but it is impossible to hate him when you see the unfairness he had to endure all his life, and how happiness seems denied to him until the very end. I didn't know this actor before I watched him here, but he impressed me from the get go: his expressions were always on point, from smug or triumphant to defeated or lost. Damn he was good also in Hidden Identity (main).

For Sweet Stranger and Me (support).  His role of a complex, wicked character made me want to watch more of him, especially as a lead role.  In Mad Dog (main), he played a scammer with cool and flair. But his best role was in My Country: The New Age (main): his performance of an unloved, lost, conflicted man stirred me hard. 

The Guardians (main) is his best work. His expressions are very him, very unique, and he breathes the characters he plays. He's even improving as his experience grows, because he's taking on more difficult roles. However, his choices recently have not been original, instead of him pursuing some more complex plots. He may drop from my top 5 should he carry on playing the stereotype rom-com character. 

For Moon Lovers: Scarlet Heart Ryeo. Played a villain with all the inner darkness necessary, but with enough subtlety that he rang surprisingly true. In Alice: Boy in Wonderland, he was just mesmerising and eerie. I wish he'd get more parts.

In A Korean Odyssey (main). He played a hot headed, cheeky, funny,  confident character I immediately fell for, and I liked him even more as the drama progressed to develop a full on crush! He's maybe not the best actor out there but I just can't help having a mega soft spot for him (the killer smile and killer looks help a lot...)
Edit: brilliant performance in Mouse. I think he's both maturing as an actor, but he's also choosing  more complex scenarios

I've watched him in many dramas, and he was on point for all of them. However, to me, his best role was in Remember: War of the Son (main). He plays an attorney who repents on his past misdeeds. An experienced, wonderful actor who impressed me more and more as the series progressed. He is my official guilty crush! 

For Strangers from Hell (main) where he plays the most chillingly cruel, softly spoken, always calm psychopath. He managed to create this uncomfortable yet mesmerising aura around him. His character was fascinating, and truly terrifying.

In Moon Lovers: Scarlet Heart Ryeo (main) and Flower of Evil (main). This man nails his facial expressions: he doesn't have to say anything to convey all his feelings. Just...wow. Wow. Superb actor. 

In Beautiful Gong Shim (main), he was confident, goofy and appeared genuinely warm and friendly. In Remember: War of the Son (main), he played a sadistic, entitled villain that I hated from his first appearance and the horrid aura remained in all his scenes. A born actor and a joy to watch.

In Algernon ni Hanataba O (main), he was astonishing, and hit me right in the feels. His best performance by far.

In Just Between Lovers (main). I watched him in Twenty (main) too, but he impressed me most in JBL. This character hid his lack of confidence behind a careless, mouthy front, but his broken soul shone through his empathy and selfless behaviour. This suited this actor perfectly: he managed to breathe life and realistic pain in his role. I just wanted to hug him and comfort him every time he showed.

In My Country: The New Age (main). This man is a scene stealer. The character he plays there showcases this man's natural authority and charisma. A born leader, able to show cold, vicious ruthlessness, yet capable to stir enough emotions in us that we can't help but feel sorry for him. Impossible character to love, yet impossible to hate.

For I'm not a Robot (main) and Remember: War of the Son (main). He nails the emotional scenes, this one, but he can also deliver funny lines perfectly. He has the same natural sensitivity as Kang Ha Neul, which is a huge attraction to me. A well rounded actor.

In Bad Guys (main). PHJ portrayed an apathetic, mysterious character with a huge amount of charisma. He didn't talk a lot but his expressions were clear and powerful, enough to highlight a darkness within him, yet sensibility, determination and loneliness still came through to make you wonder for a long while about the true personality of this complex character.

In Romantic Doctor, Teacher Kim 2 (main). Maybe he was lucky to play such an unforgettable character, written with such finesse, but this actor also input his own charisma and demeanour to the role. He literally owned it: he shone brighter in his scenes than any of the actors around him (and they were all talented). An incredible actor.

For Prison Playbook (main). This actor shows his experience and maturity. Very likeable and realistic character, far from the perfect, bland hero. Natural acting. He made me want to watch more of his work.

For The Guest (main). The charisma this guy has is unbelievable. His acting was raw, gritty and multi-layered. 

In Inuyashiki (main), where the inner conflict and the aloofness of his character really got me. Very  captivating actor. 

For Hotel del Luna (main) and Circle (main). In both dramas, he played the sweet, kind man in a soft, natural way. Both characters were realistic (especially in HDL): no perfect hero or Alpha male, just a real, friendly and engaging lead, which is refreshing in drama land.

In Midnight Runners (main). I've watched him in a few rom-coms too, but I think he handles comedy more naturally than sad or lovey dovey scenes. His best performances are of sarcastically funny, tough and confident characters: he looks more at ease on screen and his comedic timing is spot on. On the other hand, I'd love to see him in a gritty action thriller, just to take him out of his comfort zone: I'm sure he'd be awesome. (edit: watched him in Divine Fury. Shame for the unoriginal plot, but this character suited him to a T)

In Faith (main), he played a wise, modest King and he stole the show from the 1st lead. In Miss Hammurabi (support), he was funny and geeky. Extremely natural acting, and an actor that never disappoint.

For Miss Hammurabi (main), where he gave a stellar performance of a quirky, temperamental judge with so many layers he was unforgettable. Safely one of the great Korean actors out there.

In When the Weather is Fine (main). He completely suited the mellow, soft atmosphere of this drama, and played a big part in adding onto that feeling of cosiness and warmth with his acting. His character had this inane innocence and vulnerability hard to resist: his whole demeanour was touching to the point I wanted to cross the screen and give him a big hug.

For Good Doctor (main). Such a complex character. I didn't particularly like him at first, but the depth of his personality pierced through little by little, and I ended up adoring him. The typical cold exterior, warm interior character, played to perfection. Very charismatic too.

For Good Doctor (main). Such a cute, lovable character,. Joo Won managed to portray autism with finesse. His character was maybe given too many heroic deeds, but it fits the feel good storyline. Joo Won and his co-stars made the whole drama touching, engaging and vibrant.

In Children of Nobody (main). I have watched him only in comedic roles, but boy do I prefer him in serious ones, such as the cop in CON. He showed emotion without going overboard, behaved naturally and realistically. He was a character with a lot of rawness and honesty.

For Zenkai Girl (main). Very realistic and down to earth acting. He was adorable in this drama. 

In Strangers from Hell (support), he played psychotic twins, one of which had a mental impairment, and he was incredible at it. Not sure why he hasn't been offered more jobs, because this guy would deserve it

For Algernon ni Hanataba wo (support). Plays a rough, hot headed man with a big heart, and his character's growth in that series is flawlessly acted. 

For Blood (support). His character enchanted me, and he stole the whole series, which was otherwise pretty rubbish. Very dynamic and natural on screen.

For The Guardians (support).  Played a psychopath teenager. He was chillingly believable. Hopefully, it's the start of a fulfilling career.

In Guardian (support). While the series ended up being a disappointment, his character is the one that remains my firm favourite. He could have been pretty irritating and boring, as Li Yan played an overly clumsy, naive, weak young man, yet I found him touching, sweet and puppy like adorable.
I always admire actors who are talented enough to manage to turn around a character you should hate on paper into one you like. Kudos.