Lawful evil, chaotic evil, neutral evil. Im looking for an evil protag but no harem. I mean, love is fine i just dont want a harem seeking or lustful protag. Want a creul and decisive protagonist that is strong and not easily fooled. Cliches are okay but nothing too common. No idiot opposing parties pls qvq Something like I was born in Hell
https://www.royalroad.com/fiction/36804/the-devils-foundry - mad scientist supervillain got isekai'ed
If you're ok with Xianxia then Reverend Insanity. Protag is exceptionally evil, ruthless and manipulative. No harem (or romantic subplot). The only drawback is that the novel is on indefinite hiatus.
https://www.novelupdates.com/series/regressor-instruction-manual/ https://www.novelupdates.com/series/abyss-domination/ https://www.novelupdates.com/series/dungeon-defense-wn/ https://www.novelupdates.com/series/grasping-evil/
You can try The Slag Gong wants to Kill me. It's tagged as yaoi but has no romance. It a story about a man that wants to kill his cheating husband. He is literally a psychopath, that doesn't even remember people's names. Everyone is call by what the mc remembered them by (ex. Husband, Editor, officer, etc.) It's pretty short, so give it a try.
If you don't mind non-CHN ones, then maybe: Overlord Youjo Senki The Evil Organization's Recruitment Ads Seoul Station Necromancer (he's a bully)
Ouroboros Record is pretty fun. MC uses alchemy to work towards his goal of immortality. Contains slaves, human experimentation, etc.
Dungeon Defense might be evil but regressor manual and Grasping Evil(this one specifically) definitely isn't
depending on how you define evil the protag from the empress gigalo might fit as he gradually loses his compassion and casually poisons some 200 000 people to death, and orders entire families be wiped out doesn't the protag of Grasping Evil literally rape someone, or am i remembering the wrong one?
It's impossible for a Chinese novel to not have scenes of raping. Raping was never evil in their eyes since they justify it by saying "I'll take care of her for eternity and she'll never suffer as my 120582th harem girl".