There’s a I guess you could call niche? trope? in some fantasy anime/manga where the protagonist is actively trying to be a villain but is constantly being misunderstood by the people as being some sort of saint.
I can think of two different ones from the top of my head, one called “I’m the Evil Lord from an Intergalactic Empire” and another called “The Mistaken Saintly Life of a Villainous Scion”, the former fitting closer to what you asked for than the latter. Note, however, that I am not recommending either of them. The former is entertaining enough and I haven’t read the manga to give an opinion on it, but the anime isn’t that big of a deal imo, whereas the latter is just straight up trash.
Corkyskog@sh.itjust.works 10 hours ago
There is a sci fi series called the Damned Trilogy where warring space aliens stumble across humans and one faction enlists them because they are the most terrifyingly violent species they have ever stumbled upon.