I've read Reverend insanity...the mc can't really be called "evil for the sake of evil" but rather a rational and benefit driven character. But he does not feel gratitude, no feel to repay kindness, no qualms about killing the innocent for his own benefit, no emotional attachment to right and wrong. I'm not looking only for a pure evil character, but fulfils those criteria - a main character like fang yuan(mc of RI) is what I want to find. P.S. I have already read Warlock of the magus world most evil mc requests are recommended by wmw but even leylin feels the need to repay kindness. So I want even more, a more chaotic character like fang yuan. I have also looked around at the evil protagonist tag, but most of them are the same, the character is usually "evil to others and caring toward their loved ones" I want a mc where he has no qualms about killing parents, relatives, children and anyone as long as it pushes him forward.
Let's hope we find those lost and lonely novels, brother. They are banished by the cruel society, we should take as many as they come.
Well~ With Leylin, it isn't really "a need to repay kindness," the recurring theme in the world was equivalent exchange. You might want to look through the psychopath tag instead of evil.
The Mc of Dungeon Defense(light novel version) fits your criteria. Ouroboros Record ~Circus of Oubeniel~ also fits, but is a bit lighter than my previous recommendation.
The mc of Summoned Slaughterer is , as the title suggests, a psychopath. The mc of Apotheosis of a Demon – A Monster Evolution Story isn't exactly evil but more anti-hero, she becomes uncaring about killing later on in the series. (sorry for not adding links, its is my first post and it won't allow links until I have 5 posts.)
haha I'm currently also read cpod as its by the author of wmw. I rather not try a original work like them on webnovel or royal road unless its finished as most tend to get abandoned and never resumed Youjo Senki is nice, although i read the manga... its sad that the novel isnt being translated and using mtl would ruin the enjoyment in reading I've thought of reading it before, but as the author dropped the novel, I got turned off from reading it... I will try and read as much as there is
Summoned Slaughterer MC just loves to kill There are few more that comes to mind but they all are evil just to their enemy and cherishes their friends
You can try Paradise of Demonic Gods the MC has lost all emotions of love, kinship, compassion, etc, and made a place for other negative emotions.
Thriller tour group - The mc is very crazy not evil , he can do anything for excitement not rape , he is a very crazy person who can also be on the edge of death for excitement
Soul of Negary Netheril’s Glory Ascending-the-heavens-as-an-evil-god Lord of glory Hell app Tower of Karma