Geralt of Rivia (perhaps best known from the Witcher series of video games) first premiered in a series of short stories penned by Andrzej Sapkowski back in the early ‘90s. Sapkowski would go ahead and pen a series of connected novels from 1994 to 1999. They have only recently been published in English, with the final book in the saga being released in English this year.
Geralt is a witcher, a professional that deals with monsters. And he was engineered to do it. In the world of the witcher, where monsters are all too prevalent, your common person isn’t going to stand much of a chance against something that can move faster, regenerate from wounds, and decorate the nearby trees with what was inside of you. Enter witchers. They take boys, subject them to a horrible process that makes them faster, stronger, and able to withstand injecting horrible alchemical concoctions that make them even faster and stronger. They also study a limited amount of magic, and learn a tremendous amount of lore about the monsters they are supposed to fight. The process makes them immune to disease… and also renders them sterile. Traditionally, they only took young boys to train, though the central aspect of the saga is Geralt training a young woman Ciri.
The Witcher could easily stay within the concept of monster of the week. Geralt could show up, kill the local monster, and move on. He, however, lives by a witcher’s code. He won’t kill a sentient monster. He’ll only take a job for payment. The lie is that there is no codified “Witcher’s Code.” It is something Geralt refers to in order to keep people from asking too many questions, and it gives him an out in order to refuse contracts he disagrees with. Sapkowski does occasionally indulge in his characters discussing philosophy, and the fact that his characters use modern scientific terminology might be disconcerting to readers who are used to more pseudo-medieval fantasy. The setting itself isn’t real world Earth, but does take place in a setting where different planes of reality have converged in the past, and this convergence is what resulted in monsters coming over into the world.
Geralt is a thinking man’s hunter. He’s not going to swing his sword first. He investigates. He asks questions. He prepares. And if at the end of the day he decides you are a threat? Then he’ll draw his sword. He is also well aware that a foul form can hide a fair soul, and vice versa. Even though he carries two swords, one silver for supernatural foes and one steel for more mundane threats, he acknowledges early on that both are for monsters. To be sure, the stories are bit more grey when it comes to morality than what you would expect from “classic” pulp, but there are many variations on the genre, and we’d be remiss to discount them out of hand.
All in all, I’m surprised that I don’t see the Witcher series end up on more sword-and-sorcery/grimdark lists, as if you have an interest in either genre, you’d be remiss in passing them up.
 In contrast, the first video game was released in 2007. There has also been a Polish tv series called The Hexer based on the property, a Polish tabletop game, and there is a forthcoming Netflix series in the works.
 Geralt is referred to more than once as a “mutant,” for instance. Magic as well is viewed from an empirical standpoint and behaves in a consistent fashion.
 It is heavily implied that humans are not native to this world either.