Dark Horses in dramas, bad boy turned good

Could you please recommend C-drama or K-drama with main character enigmatic yet powerful, bad boy turned good, someone like 4th prince Wang So, Son-oh-Gong from the Korean Odyssey and shang Guan Qiu Yue from Love better than immortality.

 Apollymi:

You can try Untamed, Chief Kim, Fall in love wit my badboy, HuaJai Sila (but its thai drama), My dear warrior (thai drama, support character but i would say that he is second main lead), Qing Qing Zi Jin, Seven of me (only one personality was evil), The legends (its complicated, i dont want to give spoilers, if you didnt see it yet), The romance of tiger and rose, Unexpected and W-two worlds. 

Impressive, thank you.  "The legends" already in my "plan to watch" list, so maybe I will begin with it.  

 Bliss Tamar:

C-drama or K-drama with main character enigmatic yet powerful, bad boy turned good, someone like 4th prince Wang So, Son-oh-Gong from the Korean Odyssey

None of these are exact fits, so perhaps consider them "maybes": 

• Crash Landing on You - ML is a captain in the North Korean army and his father is the head of the military so he's from a very powerful family. He's mostly a good guy already, but he's definitely a badass fighter and he initially comes off as cold / unyielding, and at one point early on he does wonder to himself (not out loud so it's not for show) whether he should kill the FL. That always seemed like bad writing though and was very out of character for him and he very quickly reveals his decency and soft spot for the FL.
• Healer - Not exactly bad, but definitely grey. The ML is a man for hire who allegedly will take any job other than killing people (although we never really see him do anything questionable). He's a badass fighter but also a loner and a bit of a dork who quickly falls for the FL. 
• The Eternal Love - The ML is a prince with good skills in terms of strategy and fighting. He initially seems extremely cold and callous, but the FL quickly brings out his warm and affectionate side and he ends up choosing to prioritize love over gaining the throne.
• The Story of Ming Lan - Through a serious of unfortunate events and choices, the ML becomes leader of a group of water bandits and later on a powerful general. At the bandit stage, the FL convinces the ML to make better choices so his daughter will have a better future.
• Legend of Fu Yao - The ML is very powerful both in terms of his fighting ability and his political power (he's posing as a mortal prince, but if I remember correctly he's actually an immortal prince from a different, more powerful kingdom). He's not really bad, but he is tasked with finding and killing the FL in order to save the world from terrible fate.
• Mr. Sunshine - The FL is the daughter of a very wealthy and powerful noble family that clings to tradition and shelters her from the world, but she is secretly also a skilled sniper and a rebel fighting to keep Korea free from foreign influence or occupation. The ML is a captain in the US army who is sent to Korea as the top ranking US representative. He is also a skilled sniper. 
• The Princess's Man - The ML starts out as an innocent scholar, but political upheaval and terrible circumstances result in him becoming a rebel leader plotting revenge against the FL's father. He kidnaps and threatens the FL before learning that she didn't betray him (or something along those lines) and when he fails to kill the FL's father he eventually chooses to give up on revenge and to live a peaceful life instead.   
• Tempted - The ML is only powerful and enigmatic to the extent that a sad but very rich teenage boy who has just graduated from high school can be. He tries to seduce the FL as a cruel bet, but ends up falling for her. 

• Secret (2013) - Genres: Romance, Drama, Melodrama Tags: Rich Male Lead, Revenge, Nice Female Lead, Naive Female Lead, Hate To Love, Slow Burn Romance, Obsession, Innocent Female Lead, Rich Man/Poor Woman, Prison.
• That Winter, The Wind Blows (2013) - Genres: Romance, Drama, Melodrama
  Tags: Con Man, Playboy Male Lead, Hidden Identity, Blindness, Stolen Identity, Gangster, Star Crossed Lovers, Death Of A Parent, Separation At Birth, Gambler.
• The Innocent Man (2012) - Genres: Romance, Drama, Family, Melodrama
  Tags: Revenge, Character Development, Strong Female Lead, Rich Woman/Poor Man, Makjang, Male Chases Female First, Cold Female Lead, Rich Female Lead, Seaside, Deception.
• The Legend of the Blue Sea (2016) - Genres: Comedy, Romance, Drama, Fantasy Tags: Interspecies Romance, Mermaid, Naive Female Lead, Reincarnated Lovers, Eccentric Female Lead, Con Artist, Evil Stepmother, Housemates, Woman Loves Eating, Hidden Identity.
• Tempted (2018) - Genres: Friendship, Romance, Youth, Drama, Melodrama
  Tags: Rich Male Lead, Bad Man/good Woman, Bromance, Hardworking Female Lead, Second Chance, Revenge, Naive Female Lead, Betrayal, Idol Actor, Heir.