Circle, if I really wish well for the person I'm recommending the drama to. The list ends there.

I’ve started all the dramas here, but only finished MOA (for Hyun Bin) and MRISG (which just dropped on Netflix US). Can only give MOA a tepid recommendation because it started with a premise that was original and the first episodes were interesting, but it got bogged down in the middle, trying to make it a romance that didn’t work for me—the chemistry between the leads just wasn’t there. And the ending I don’t even remember except it seemed to end in a church? And didn’t Sisyphus end in a church too? And PSH was in that too? Maybe that’s why I’m getting it confused. I’m sure she’s a wonderful person, but I just have never found her very engaging.

I did love MRIAG. I’d very much recommend it for a nice watch with a good cast, good kissing and chemistry, and pretty people to watch. And there is a cameo of my girl Jung So Min. I found this very watchable from beginning to end.

I had forgotten how much I loved (the first half of) W. Lee Jung-seok has an incredibly believable manhwa character face and he was so charming in the role. Han Hyo-joo was equally lovely. As for the story, the part right up to him jumping off the bridge is brilliantly paced and raises important questions about the role of a creator. But sadly it goes downhill from there.

Ending badly is almost a tradition in fantasy kdramas (remember Hwayugi anyone?) so I prefer dramas with a lighter fantasy element like While You Were Sleeping.

For the suggestions :
- W-Two Worlds : I remember that I really liked the beginning until the middle of the drama, then the story completely lost me. But the main couple was great.
- Memories of the Alhambra : It was one of my favourite Hyun Bin's drama, for me, he was perfect in this role, the story really rested on him. Therefore, it was kinda disapointing for Park In-Shye. I loved the fact they filmed a lot in Spain, it was so beautiful. I liked the mix between the reality and the game. The brother's arc was disapointing and didn't really make sense.
- Hotel del Luna : I really liked it. It was beautiful and the OST was great.
- My Roomate is a Gumiho : the difference of age, the fact he was a professor and the way she was calling him made things difficult for me to root for this couple. Kang Hanna was the best part!
- The King : Eternal Monarch : I didn't really like the chemistry between the main couple, so I couldn't immerse myself in the story. I didn't like how they chose to solve the issue. At least, we got 2 doses of Woo Do-Hwan \o/

Other suggestions :
- Extraordinary You : Kim Hye-Yoon was the best high-school student in Kdrama. I really liked the idea that the characters were in a manhwa and they tried to navigate between their own will and the writer's will.
- Goblin : I really liked the worlding of the story. The actors, the scenery, Canada and the OST were great.

Mystic Pop-up Bar, just to add to the list.

I will always love Queen Inhyun's Man,
and I second Goblin and Mystic Pop-up Bar

The King:Eternal Monarch is the absolute definition of guilty please... its objectively terrible, the male lead has the emotional range of a toaster , but i still enjoyed watching it, even with its nonsensical ending.

I'd like to throw in Strong Girl Do Bong Soon, the execution was far from flawless but the set up was fun and Park Bo-youngs comedic timing was on point.

While you were Sleeping
was another good one, its the only Suzy performance I would classify as "good", a solid fantasy and a fairly good romance too

Angels Last Mission
The ending was unsatisfying and the final stretch was a bit too angsty but Shin Hye Sun always delivers the goods, she's great here and her male lead was no slouch either

The first 6 episodes of Memories of Alhambra were amazing and I absolutely loved the cast. Hyun Bin, Park Hoon, Lee Jaewook, Lee Hakjoo, Lee Re, Park Haesoo, I could go on.
It's a shame that drama lost its way. And Park Shinhye really didn't deserve to be flower-potted so hard, what a waste!

Now that I think about it, I do watch quite a lot of fantasy dramas 🤔
Just to mention some recent dramas, Mystic Pop up bar is one of my favourites.
Zombie detective is very light and fun, and, on a more high-end style, Tale of the Nine Tailed and its variety of supernatural beings was a fun watch. School nurse files is also a standout, but maybe not to everyone's taste. Finally, Extraordinary You was very fresh and original

I would add Daebak Realty and Mystic Pop Up Bar.

I think Circle is the best fantasy drama but Extraordinary You and Scripting Your Destiny were also well made shows.

I quite enjoyed W, Alhambra & HdL, but there are lots of fantasy shows I liked more than King or Roommate (except Kang Hanna's scenes, of course)
Mystic Pop Up Bar
Strong Woman
Master's Sun
Queen In-hyun's Man
Bring It on Ghost
Splash Splash Love

This list feels a bit…recent. Not that there’s a problem with that, but I wish some older fantasy dramas were also included.

Queen In-hyun’s Man (2012): The absolute perfect blend of epic romance, time-travelling shenanigans, and excellent character writing. Kim Boong-do is still my favourite male lead any drama has ever had.

Arang and the Magistrate (2012): A Joseon-era fantasy that actually works. There are gods and monsters and grim reapers and ghosts - and it’s brilliant and funny as all hell.

Master’s Sun (2013): More on the horror-fantasy/comedy side of things, but definitely worth checking out.

I Hear Your Voice (2013): Maybe not fantastical enough, but the hero can literally hear your thoughts so I’m putting it on the list.

Splash Splash Love (2015): I recently rewatched this and was amazed at how well it aged. Short, but satisfying and sweet. Still haven’t given up hope for a reunion between Kim Seul-gi and Yoon Doo-joon in a full-length drama. A girl can dream.

Signal (2015): Again, not very fantasy-heavy, but it’s got a magic walkie-talkie that communicates across time so it counts.

Circle (2017): As @wapzy said.

Chicago Typewriter (2017): Who even am I if I didn’t push Chicago Typewriter into as many lists as possible? There is a ghost, a magical typewriter, and reincarnation. I’ll make it fit here goddamnit.

Hwayugi (2017-18): Objectively not good, but the definition of a guilty pleasure for me.

I know a lot of these aren’t very old, especially to people who’ve watched dramas from before 2010, but that’s around the time I started so my preferences skew 2010s-ish. My more recent recommendations would be:

Extraordinary You (2019): I fully believe this will become a cult classic years down the line. So many well-known rookie actors.

School Nurse Files (2020): Won’t be for everyone, but a blast for those who do get it. My favourite Nam Joo-hyuk for sure.

Scripting Your Destiny (2021): My surprise favourite from last year. Shockingly underrated despite how good it is.

I’m just here to say that even though it is from an older and cornier time, My Girlfriend Is A Gumiho is the superior gumiho drama.

Lol I didn't like any of these. Okay alright, W's first half gets a pass and MOA was fun but really only because I sh☠️tposted it.
Fantasy Kdramas are a bit of a catnip for me but I'm also very fussy and critical about the Fantasy genre as a whole so it's a rocky relationship that often leads to the aforementioned sh☠️tposting. RIP.

My fantasy reccs go:

1. Mystic Pop Up Bar
- actually, this is like the gold standard of fantasy dramas for me at the moment. 100/10 recommend over basically anything else here.

2. Sell Your Haunted House
- I'm beginning to think though, looking at this list that "uses horror as an effective supporting narrative tool to the fantasy genre" is important in what I look for in fantasy lmao

3. Arang and the Magistrate
- This is still such an underrated fantasy drama and I've been saying this for years.

4. Tale of the Nine Tailed
- say what you will about the rest of it but I love it and if I have to put this on here for episode 9 alone, I will.

5. Splash Splash Love

6.Queen In Hyun's Man

7. You From Another Star
- I have NO idea if it holds up today but a frakking classic! Come on! And the only drama I've ever cried in somehow!

8. Look I know it's a hot mess and a trashy guilty pleasure but you can't beat Lee Seung Gi as the Monkey King so, for that, and the supporting cast alone, Hwayugi.

9. If Zombies count for Fantasy then how has Kingdom not been mentioned yet.

I know this is... pushing it a little bit but if we venture into the realm of "Fantasy diseases suffered by a lead character" and an overall what I like to call "kdrama fairytale" vibe then honestly --
Secret Lyfe of My Secretary and I Am Not A Robot take that cake with no competition.

Oh and 10. My Epic Fantasy Silla Sageuk that doesn't exist yet

If horror/ghost-y elements counts as fantasy, I’m going to put in a vote for Bride of the Century. It is not for taking seriously (he has a secret family curse which means the first wife of the eldest son dies! She is the doppelgänger of his arranged fiancée and is impersonating her at fiancées family’s request! They fall in love! The second male lead is fiancée’s brother and he falls in love with her too because it’s completely normal and in no way weird to fall in love with someone who looks exactly like your sister and is pretending to be her!) but it is really good, it surprised me a lot.

W is good but turn disappointing towards the end imo

My preferred sci fi dramas are probably these:

Circle: This is a really good sci fi
365: Repeat the year :The best sci fi when it was aired tbh. what Alice wanted to be but failed miserably
Signal : I still hoping for S2
Tunnel
Missing the other side : quite underrated. I hardly see this drama in any list but it is good. heard there will be S2

Hmmm... If I was to recommend five dramas with a dose of fantasy, I'd have to go with these ones:

W: Two Worlds - I totally agree with DB on this one. I loved this drama to bits and pieces for a long time. Even then in some deep corner of my psyche I knew it wasn't perfect, but I still loved it. And I still do--yes, I admit that it's not perfect now. It's a bit rough around the edges sometimes... but it's consistently twisty and turny... and unlike a few other people here, I don't think I ever got confused about the drama. Super fun concept, fun execution, confusing final episode.

Mystic Pop-Up Bar - I think I may be a part of the minority here, but I enjoyed MPUB a lot more than it's contender Hotel De Luna. Hotel Del Luna fell flat for me because I never fell in love with Jin Goo's acting. The drama felt gorgeous, but let itself get caught up in the videography and thus I felt the story lacked something. MPOB on the other hand was a silly, crazy romp the entire way through, but had some deeper emotional beats that really spoke to me.

The School Nurse Files - I need to read the rest of the comments, but I was surprised I didn't see this one right off the bat! I loved the School Nurse Files. They were downright ZANY, but felt like they knew exactly what they were going for and I respected that. I only wish there was more of it to watch.

I Hear Your Voice - I love all the LJS fantasy dramas out there, but this one I think did a really good job with the fantasy element. Although I like the plot and loveline of Pinnochio more, I really appreciate LJS character in this drama and his portrayal of what it would be like to read minds.

The Witch's Diner - Although it's the last on this list, I think the Witch's Diner is the most fantasy-like of all my recommendations. It's the only one with a straight up witch and spells, after all. Super cute show, and I appreciated that they didn't just go for the vanilla "and they got their wish, no consequences" route. I heard they might be getting a second season... anyone know anything more?

The only reason why I didn't include titles like Tunnel, Signal, Circle, Train, Hometown, My Love from Another Star, Queen In-Hyun's Man, Nine: Nine time travels, and other wonderful titles here is that they all seemed a bit more in line with other genres like time travel (not necessarily fantasy?) or sci-fi. :)

Did anybody mention Are you human too?. Kang Seojoon befriending a Roomba vacuum and (double-)winking lie detection feature were great. Drama had its kdramey flaws, but all in all it was very fun and sweet

Ah, fantasy... My most favorite genre in almost any form of story telling (well, I am wary of it in k-drama, but even then, I usually can't help myself).

Talking about fantasy reminded me of writer Song Jae-jung, though, especially since there are 2 of her dramas mentioned above. She is like that emotionally abusive lover who enabled my boundless addiction for fantasy, promising the boldest and most interesting premise only to mess it up a few steps before the final, sent me home with grief and trauma, and left me swearing up and down that I would never touched her drama ever again. And then a year or so later she would come back with another shiny new story, something no other writer have attempted before, and I would come back to her just as quickly despite knowing the almost guaranteed pain and frustration at the end of the journey.

Sigh...
When is her newest drama due again??

So many excellent rec's in the above comments - another couple to throw in the ring:

Go Back Spouses: Utterly fantastic, kicked me in the feels almost every episode but that might just be the Jang Nara effect.

18 Again: I don't think I have ever laughed so hard and cried so much in a drama. The cast was amazing and Lee Do Hyun was a revelation.

Sweet Home: Look, this one is more of a personal indulgence, it's good campy, horror fun. Also Lee Shi Young's back muscles make a very important cameo. Honestly unsure why they didn't make top billing.

Not sure if this counts, but Another! Oh Hae Young: Hilarious, heartfelt and was my first glimpse of Seo Hyun Jin who knocked it out of the park.

I believe that I don’t care for the fantasy genre. But then I realize how much of the kdrama I love is “fantastical” when trying to describe a show to someone who doesn’t watch kdrama. Try describing CLOY or Mr Queen, for example 🤨 Or Happiness. Or YFAS, Oh My Ghost, Beauty Inside (movie version). Not exactly 100% grounded in everyday life, let’s say. Apparently I like fantasy very much 😁

W is definitely one of my favorites!

"Memories of the Alhambra" was my first k-drama and that's why it has a special place in my heart, even though I'm totally aware of its faults. There were plot holes and the locations in Europe were a total mess (I'm from Spain and I could see that many places were not Granada, or even Spain) but I got hooked to the story of that man and that woman and all the suffering they have to endure.
In my opinion, Hyun Bin has never been better than here. His acting is superb.
Btw, the love plot worked for me too.

"W: Two Worlds", from the same writter, has too many plot holes. I liked it but I prefer "Memoirs of the Alhambra".

My favorite fantasy dramas up to the moment are "Live up to your name", "Go back couple" and "The best hit".