Haechi is on equal theme with OBY.
Damo is a very good one.
Try out the just concluded Agency.
Iron Empress perhaps if you have the stomach for action sequences crazier than OBY, Damo and Haechi combined.

Han Ye-ri in Nokdu Flower
Kim Hye-soo in Hyena
Kim Mi-kyung in Healer

Nobody Knows, Lookout, The Uncanny Counter.
Yayy for kickass ladies!

Some ideas:

- Queen Seon Deok.
- Six Flying Dragons.
- Happiness.
- Secret Garden.
- Strong Woman Do Bong Soon.

Sae Beom in HAPPINESS!

In sageuk-land, there is Mr. Sunshine, where Ae-shin is pretty much the coolest sniper ever and Hina/Yang-hwa is awesome with a sword. There is a scene where they face off that is beautiful, but many more times when they are fighting other folks and being amazing while doing it. There is also The King’s Affection, where Dam-i/Hwi is trained in all the normal ways a crown prince would be, including sword and bow skills. In Alchemy of Souls there are a couple powerful women, like the Jin women and Naksu/Cho Yeong, though I know some Beanies were disappointed because they wanted them to be powerful in other ways.

Man-wol from Hotel del Luna fits this nicely too. She was an awesome warrior back during her normal human life, and now that she’s 1000 years old and has ghostly abilities, she’s even more powerful.

For detectives we have Soo-hyun from Signal and Tae-goo from Through the Darkness, both of whom were great characters - awesome at their jobs and figuring out how to navigate a male-dominated working environment.

And my final shout out is for Hyeon from Search WWW and Seul-gi from Never Give Up. Both of these women did martial arts more as a hobby, but it was important to who they were, and they both had a strong sense of justice and what they needed to do to contribute to it.

Awaken : The FL is a cop and she had some good fights.

Tomorrow : The FL was super badass !

Iris : The SFL was a North Korean agent and a killer.

Ha Ji-Won in a lot of her dramas !

The King's Affection : Hwi as a Crown Prince, she needs to know how to fight.

Any character played by Bae Doona. I think she out-badasses anyone I can think of, whether she she is wielding a sword, taser, gun or just her force of personality.

Honorable mention: Lee Byung-hoon's heroines. Given what he puts them through over 50+ episodes each time out, their perseverance is superhuman

Ha Ji Won’s Kim Hang Ah in “The King 2 Hearts” really stands out as a character whose fighting skill and no-holds-barred approach are central to the drama from beginning to end. My fave quote, as she threatens to stab herself in the jugular if her captors don’t follow her wishes: “Don’t fool yourself. Up to now, it’s not that I couldn’t be killed. I chose not to die.”
More recently, in “Love to Hate You,” Mi-ran is a one-woman wrecking crew out to destroy misogynistic creeps, from cheating boyfriends to catcalling harassers.

Hyena - she is just awesome!!
Happiness - major girl crush.
Rookie historian - doesn’t really kick ass. But her character was the reason I watched a Saeguk.
Uncanny counter.
Secret Garden and Kings of Hearts.

p.s I just can’t remember character names.

Both female leads in Capital Scandal, Bae Do Na in Forest of Secrets 1 & 2, Go Hyun Jung in H.I.T. and Han Ye Ri in Six Flying Dragons come to mind. While they're not k-dramas, the Chinese shows A Dream of Splendor, The Rise of Phoenixes and The Imperial Coroner all feature some great female characters who can hold their own in a fight.

Have you seen Krystal in Search as a bad ass lieutenant in a special team? Its nice seeing her in a totally different character once in a while. Her character is tough and ruthless.

Also do not forget Han Hyo Joo in Happiness,

Lee Si-young in Wild Romance and Lookout (and there's her amateur boxing career, so she really can pack a punch!)
Ha Ji-won in Empress Ki and Damo and Secret Garden and King 2 Hearts...

Most recently, Love to Hate You—so fun!

Maybe not kickass in the actual fighting sense, but Weightlifting Fairy Kim Bok-Joo.

Happiness has strong, powerful and efficient FL.
Ha Ji-won is kind of specialized in kiss ass role, no ?
The recent Love to have you has a FL who is not reluctant to give a beating.

Lee Yu-Ri has a very physical comedy acting style in the last few of her drama series.

Lee Si-Young is a former boxer. She has been starring in many action movies.

The one who is best at kicking a***, supernatural or what not is Gil Young. she saved the guys multiple times. The Guest Is The Best.
And Nobody Knows' Young Jin.

Agree with "My Name," probably the baddest female heroine I've seen. And, who can forget Kim Tae-ri in "Mr. Sunshine."

Kim Seo-Hyeong as the cruel tutor in "SKY Castle."