The Worst of Evil

Same vibe , 2 cops that infiltrate to a gang and try to hide their identity. Both coming from poor background. Lots of fight scenes.

Luo Xiang, a former narcotics agent, faked his death during an undercover operation. Five years later, he's living under a new name, but needs to pretend to be his old self and once again infiltrate the drug cartel, dealing with his former lover, brothers and enemies, to finally successfully complete the mission and find out who's pulling the strings.

Both deal with undercover crime investigations. Similar gritty and gripping stories. Cruel City was a little less organized with its plot and The Worst of Evil had a better setting/cinematography overall, especially being set in the 90’s. But if you liked one, you will probably enjoy the other.

If you like TWoE, you will like Evilive.
You don't have to trust me, but you can try it. It definitely worked for me.
It's a:
"good guy in a bad environment turns slightly worse" trope
"madness behind handsome looks" trope

Basically if you like dramas about undercover cops infiltrating cruel gangs with damn good action, try it!

Set in Seoul in the 1990s, a former DJ starts selling a new powerful drug nicknamed "Gangnam Crystal" in city nightclubs after mastering a gangster organization. Since the police know little about the origin of such drugs, in order to crack down on this rampant drug trafficking organization, rural police officer Park Jun Mu is assigned to sneak into the organization, only to discover that his wife, Yoo Eui Jung , also a detective, has volunteered to participate in this dangerous mission and seems to have an unspeakable past with the heinous underground drug king. Park Jun Mu in this drug-related mission, not only does he wholeheartedly fight the drug cartel, but also works hard to protect his wife's safety at all times.

- The plot is similar as it gives the similar vibes
- ML is an Undercover Cop (TWOE - Drug Trade , NW - Crime Organization)
- ML tries his level best to catch criminals before his identity getting exposed

Both involves the main character as an undercover cop infiltrating a crime syndicate. Difficult situation of preventing identity from getting exposed.

- The plot is similar only difference is this happens inside the prison
- ML is an Undercover Cop but in the prison he comes to take revenge on those who killed his younger brother
- ML tries his level best to catch criminals before his identity getting exposed

- The plot is similar as it gives the similar vibes
- ML is an Undercover Cop (TWOE - Drug Trade , TM - Crime Organization)
- ML tries his level best to catch criminals before his identity getting exposed

- The plot is similar as it gives the similar vibes
- Only difference in Insider is that ML is an Undercover Judicial Trainee for investigation in crime and gambling world
- ML tries his level best to catch criminals before his identity getting exposed

Preety similar concept
ML is same for both drama and some of the supporting cast
Action, thriller, crime, mystery
Something related to Gangnam, ganster & all

Both of these series are very dark, action-packed, and keep you on the edge of your seat. In both cases, one of the main characters is a cop and is pursuing the other main character, a criminal. This one has a hint of bromance but mainly in the flashbacks.

Other than that, this one doesn’t involve undercover cops or drugs but the vibes are similar.

Both productions have a similar premise where policemen go undercover to catch the drug lords, earning the trust of gangleaders and climbing the ranks rapidly

Although I have not watched the drama The Nice Guy this synopsis of the nice guy reminds me of the events happening in the worst of Evil. That is in terms of the gangster life and the romance of somebody who's not involved in the gangster life