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The hero was betrayed by his country and executed. Somehow he was revived and decides to seek revenge
Cool guy everyone he kills/hurts is super corrupt and they have all committed horrible deeds so I don't feel bad for any of them. Especially when they don't even have a valid reason as to why they acted the way they did

Cale wakes as a minor villain in a novel. He tries to change the course of events to give him a leisurely life.
Cale is a cunning and chill person. He uses the negative traits his character was given to his advantage. Also, he will always get other people to do the work for him if he doesn't have to do it himself. He doesn't steal the Choi Han's (the OG novels MC) sidekicks but gathers his own.

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When Kim Dokja finished reading the last chapter of his favourite novel his world turns into that novel. He has to survive and ensure the survival of the original MC.

After clearing the final level of the Shadow Labyrinth, Desir and his comrades are killed. Desir returns 13 years into the past and decides to gain allies and train to survive this time around
This series is pretty interesting. There is romance as the MC has one end game ship and as far as I know two potential love interests. Romance is a minor subplot in this
Note: The creator of the manwha does not like the main love interest of the novel and may change the manwha in favour of the other

All Gamin wants to do is study but all he is good at is fighting
There is a variety of martial arts present in this which is pretty cool. I did find the teachers character annoying with her actions and mindset.

After waking up as a villain that is killed off in a webnovel, Yoo-Sung Choi goal is to survive and become powerful enough to live comfortably
If you like Trash of the Count's family, ORV, or series similar to those this one is also pretty good. The MC is smart, strong and fairly charismatic. There's no romance but there's a lot of bromance/tension between him and the hero of the novel

"Dungeons" and monsters appeared around the world and "players" awakened their powers. The MC joins the Messiah Guild, who's guildmaster/hero vowed to save the world. In reality, the guild had no intention of saving the world and killed anyone who stood in their way, including the MC. Now that he has returned to the past it's time for him to get revenge.
The MC is cunning and cold. The best way to describe him is an "anti-hero".

Reincarnated a side character and young lord Jared, the MC, decides to use his previous life's knowledge to become the best of the best
The first season had good art and the pacing of the story was nice. But in my personal opinion the art in the second season got a lot worse, and the plot was borderline harem-y (Like all his retainers are pretty much women).

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After the world was turned into a game Kim Sehan won, but was the only one left standing. He was given a 2nd chance and travelled back in time to the day it all began
Smart and strong MC. The female side characters are well written as they are strong and independent (They do not rely on or inhibit the MC).