The first one I could think of is Cho Seungwoo's character in Life, Director Gu Seunghyo. He outshone Lee Dongwook's character in that show.

Then Han Sukkyu's character in Watcher, Do Chikwang.

Ahn Bohyun's character in Military Prosecutor Doberman, Do Baeman.

Ji Changwook's character in Suspicious partner, Noh Jiwook.

And the latest one, Jung Ryeowon's character in Midnight romance in hagwon, Seo Hyejin.

If you watch cdramas, I can’t recommend Lost Track of Time enough.

It is a rebirth revenge drama. The FL falls in love, marries, and helps her husband become emperor. His greed for power overwhelms her and leads to her death, and she wakes up the day she first met him.

I recommend it wholeheartedly because the emperor is so completely flawed and so completely compelling. The actor carries an already good drama and elevates it to the stratosphere. To me, while it is a satisfying revenge drama, I am just so drawn to the emperor that it becomes more of a story about him, about salvaging his soul. I love it

kdrama rec.. The Smile Has Left Your Eyes

Some of my favorite shows with compelling morally messy characters are Queen Seondeok, The Devil (Lucifer), Giant and Six Flying Dragons. If you're ok venturing into c-dramas I also highly recommend The Untamed.

I have not seen My Liberation Notes yet, so I don't know this is the type of character they are looking for, but my favorite "flawed but charming character" ever is Bidam (Kim Nam Gil), from the great sageuk Queen Seon Deok.

A totally flawed lead, and yet have a really magnetic pull?
When we think of "flawed" it would mean blemished, damaged, or imperfect in some way: or having a weakness in character.
The first person I thought of was Man-Wol (IU) in HOTEL DE LUNA.
I cannot think of another actress who could have pulled us so into this fantasy story so well and hold her power and charm to the very end.

I don't remember the character's name, but Lee Joong-ki's role in Flower of Evil might match your description.

For comedy, I'd recommend Chief Kim. Both male leads (Namgoong Min and Junho) are flawed but charming in complementary ways!

For legal dramas with a side of intense sexiness, you can't go wrong with the female lead in Hyena (Kim Hye-soo). So charming. So irresistable.

For a "Sunday Night" watch-it-with-the-whole-family drama (if your family likes really sweet love with a side of psychopaths), I'd suggest Brain Works. The male lead here (Jung Yong-hwa) is a brilliant neurosurgeon with issues of his own.

For an action-tech-comedy-drama, and supporting characters rather than leads, look no further than Ma-pi (Kim Sung-oh) from Unlock My Boss.

And last but not least, for home-appliance-manufacturer-based dramas, most characters in On the Verge of Insanity fit this bill, lead or supporting, gender-blind. No, seriously, this is one of the best dramas of the past five years, hands-down, in part because pretty much whole cast matches your prompt.

Forgot one so reposting:

When I think of MLs who are deeply flawed but with towering, absolutely adorable personalities you end up falling in love, it's two Crown Prince turned Kings from two shows:

Yi Sun from The Red Sleeve
Yi Hwan from Our Blooming Youth
Lee Gang Doo: Just Between Lovers (probably the best fit so had to add this)

For female leads, Gil Chae from My Dearest leads the race by a huge margin.

For supportive characters, Maeng Du-Ri from The Matchmakers
and Choi Soo-yeon from Extraordinary Attorney Woo.

Jung Geum-ja (Kim Hye-Soo) - Hyena
Kang Ye-seo (Kim Hye-Yoon) - Sky Castle
Yo Han (Jisung) - The Devil Judge
Jung Sun-ah (Kim Min-Jung) - The Devil Judge

and.... Lee Yoo-ri in all her makjang dramas

All our female leads from both seasons of Age Of Youth but specially Park Eunbin's character (I don't remember her name sorry!!)

Cho Sanggu from Move to Heaven and Park Joong-il from Tomorrow - both characters had a very redeeming arc by the end of their shows but I still remember wanting to smack them around during the initial episodes of their respective shows.

What do you mean, "flawed"? I mean the entire super-hero family as well as super-con family were only charming, right? My favourite was "uncle". He had chemistry with literally every member of the Bok family 😂

I accidentally posted this comment in the wrong prompt. In case you are wondering those families appeared in The Atypical Family. Not one person in both families without "flaws" 🤭

Lee Sung Min in Miss Korea.

Yoo Jae Myung im Forest of Secrets.

Jo Jung Suk in Jealousy Incarnate.

Lee Si Young in Lookout.

Kim Min Jung in My Fellow Citizens.

Kim Hae Sook in Marriage not Dating.

Lee Sung-min in Reborn Rich and Shadow Detective.

Lee Joong Ki in Scarlet Ryeo. Man oh man was he flawed, but that drama still breaks my heart, but Chef's kiss for its brilliance, when it was good it was spectacular, when it was bad, yikes.

Jealousy Incarnate : Jo Jung-Suk was so charismatic in this role.

Mr Sunshine : Yoo Yeon-Seok played a pretty violent character on the Japanese side.

The Interest of Love : Moon Ga-Young played a flawed character but so well, I felt a lot of empathy for her. But every character was flawed.

The Smile Has Left Your Eyes : One of my favourite role for Seo In-Guk.

Come and Hug Me : Kim Kyung-Nam played the older brother and had a great arc, my favorite part of this drama.

Not antagonists, so like antiheroes? Then I would say Vincenzo.

One of my top dramas of the year LTNS. I’d argue both our ML and FL are flawed and are the antagonists in the show. Tho, I have to say my favourites tend to lean toward the flawed and messy Female Leads. From the same writer as MY LIBERATION NOTES, ANOTHER MISS OH. The FL Oh Hae-young is unafraid to show her emotions while processing the fact her fiancé dumped her during their wedding preparations.

Recently rewatched DISCOVERY OF LOVE, and how I miss Jung Yumi in kdramaland. All three characters in the love triangle are frustrating but my heart goes to our FL Han Yeo-reum, it’s a polarising drama for sure but that’s what I love about it.

I would be remiss if I didn’t mention BO-RA! DEBORAH, she’s a dating coach which should already be sending off alarm bells. Her dubious dating advice backfires on her as she catches her long term boyfriend cheating on her.

ALCHEMY OF SOULS at least S1. Jung So-min’s Mu-deok is a treat to watch, a once deadly assassin relegated to teaching our hopeless ML Jang Uk.

Bidam and Mishil from Queen Seondeok own this thread.
Also Lee Bang Won (Yoo Ah In in Six Flying Dragons and Jang Hyuk in My Country)

Gu Dong Mae (Mr. Sunshine), although "charming" is not exactly the right word for this character.

Kim Bum's character in Tale of the Nine-tailed. His charming true villain-wannabe-but-just-wants-to-be-loved portrayal is spot on!

Junho in Chief Kim someone's already mentioned, but he's perfect.

And my all-time favourite actor to mention! Wang Duo in Cdrama Bloody Romance. I don't think dramaland has ever seen a more morally ambiguous character than prince Ning.

Jang Hyuk in Money Flower and Country (as Lee Bang Won)
Nam Goong Min as Chief Kim and Doctor Prisoner
Lee Junki in Flower of Evil

Dae Gil (The Slave Hunters).

Jang Hyuk is really good at playing flawed but compelling characters: Money Flower, My Country, Thank You, Robber

Lee Sung-min has been mentioned a lot, I'll throw in his character in Memory. He really can play the gamut of flawed but compelling characters.

Lee Dong-wook also has a bunch, I like his comedic playboyish roles like in Partner and Wild Romance, but he has a lot of tortured ones, too (one of the more interesting ones is Blade Man). And of course there's his Dour Death in Goblin.

Cho Seung-woo plays two different types of flawed characters in God's Gift: 14 Days and Forest of Secrets, which also has one of the great flawed characters by Yoo Jae-myung and comically flawed by Lee Joon-hyuk (I was rooting for him in Season 2).

I'm short-shrifting the female characters, but you can't beat Go Hyun-jung in Queen Seondeok and The Queen's Classroom, Lee Bo-young is good at comedically shallow (I Can Hear Your Voice) and repressed emotional trauma (Mother, My Daughter Seo-young).

There are some shows where both leads are flawed. Nice Guy was delicious. Que Sera Sera was like watching a trainwreck. In Ruler of Your Own World everyone's got issues but that show turned me into Yang Dong-geun fan and I was really moved by Youn yuh-jung as his mother.

And finally, So Ji-sub in I'm Sorry I Love You.

My Liberation Notes' Mr. Gu was who first came to mind.

The lastest flawed but charming character on my screen is Bitter Sweet Hell's Hong Sa-kang.

Delving into my books... a long list includes:

Life : Jo Seung-woo
Queen Seondeok : Go Hyun-jung
On The Verge of Insanity : Lee Sang-yeob
Emperor - Owner of the Mask : Yoon So-hee (Kim Hwa-gun)
Queen of Divorce : Oh Min-seok
Tell Me That You Love Me : Kim Ji-hyun
Bloody Heart : Jang Hyuk
Bloody Heart : Park Ji-yeon
The Matchmakers : Park Ji-young
Little Women : Wie Ha-joon
The Midnight Romance in Hagwon : Seo Jung-yeon

The prompt is quite vague or is it just me? Like are we talking about grey protagonists, charismatic villains, charming supports or everyone above? Because that's 3 separate but equally loooong lists...

I thought Kdrama's speciality lies in flawed characters that somehow make me root for them, villains included!
Definitely at the top of my mind right now would be our Atypical Family, especially the sauna side of it. There were so many times when I was yelling at Sauna Mom and Gym Sis, embrace your good side, woman - you know it's right there! The uncle was also so cute throughout.
Also, Lee Min Ki's cop from Behind Your Touch, and Seo Ye Ji's FL in Its Ok to Not Be Ok. There are many many more, but I can't pinpoint at the moment.
In Cdramas, I'd def add the FL from Will Love in Spring, and Elvis Han, in Fake It...

Shunji in Gaksital - you could say villain, yes. but the why? and yet...
Min in Hello Monster

I don’t know if this really fits the prompt but Shin Sung Rok in the Last Empress was pretty clearly Not A Good Person but he was way more compelling than the actual hero 😅

Con artist Seung-Jung in (Kim Jung-Hyun) Crash Landing on You may have done some dirty deals, but his ultimate sacrifice made him a much-beloved character.

Another swindler, Yong-Tae (Son Ho-Jun), in My Secret Terrius might have stolen my heart instead of the ML—had the ML not been So Ji-Sub.

Prison Playbook had a whole cell full of criminals I grew fond of during the course of the show, though aside from Jung Hae-In as the homicidal Captain Yoo, I wouldn't call any of them "magnetic."

Jang Hyuk has played a number of flawed characters who exert the kind of magnetic pull described in the prompt. In addition to the already-mentioned Bloody Heart, you'll find him in roles including obnoxious chaebols (Fated to Love You, Bright Girl's Success), gangster (Greasy Melo), and a man who resorts to crime in order to support his children (Bad Papa).

I would say Ko Nan-do from My Holo Love. He's soooo flawed but you end up loving and rooting for him.