Be it demons, vampires, werewolves, or what have you, some species of creatures have been viewed as malevolent, particularly by those belonging to an Abrahamic religion (e.g. Christianity). However, some members of these species are actively going against said stereotype: they have a healthy respect for God, and they may even follow His teachings more than the humans around them, even those who share their goals in some way, shape or form. Even if they're villains, they can still believe in and worship God.
Super-trope of Religious Vampire. Compare Religious Robot, when a product of science is a person of faith, and Heaven's Devils, for literally demonic beings who serve God's cause in some way. Not to be confused with Sinister Minister and Churchgoing Villain, for more figurative monsters who venerate God. Compare Fantastic Religious Weirdness. Sub-trope of Religion Tropes (in general), and Otherness Tropes.
- Blue Exorcist: Rin and Yukio are Ambiguously Christian, having been raised by a priest in a monastery. They're also the sons of Satan and Rin is an Anti Anti Christ.
- Chrono Crusade is about a demon and the nun who struck a bargain with him. They fight crime-um, that is, other demons on the say-so of the Church.
- Goblin Slayer: The Goblin Paladin is part of the Always Chaotic Evil goblin race, yet he worships one of the setting's non-evil deities. Because of this he lacks the innate cowardice of his kind, being an Evil Genius with the bravery and charisma to serve as the Dark Messiah for the race. This all makes him one of the most dangerous goblins out there.
- Blue Devil is a devout Catholic who also happens to be possessed by a demon. Unfortunately he tends to singe in churches due to his demonic traits.
- Hellboy: The titular character is a demon who follows the teachings of some ambiguous religion (stated to be Roman Catholic in the film adaptation). It's telling that unlike with other demons, Holy Ground has no effect on him.
- In Runaways, Victor Mancha is a robotic killing machine who is also a genuinely devout Catholic
- Nightcrawler from X-Men is a blue-skinned mutant who resembles a demon... and happens to be a Roman Catholic.
- Confessor from Astro City is a vampire who was a Catholic priest and now acts a superhero. The cross her wears on the front of his costume constantly burns him, which he regards as form of penance.
- Dark Angel: The Ascent: Demons are portrayed not as completely malevolent monsters, but essentially the jailers of Hell. They're a religious sort who worship God and pray before dinner.
- One of the only moments where Plan 9 from Outer Space briefly edges into actual, thought-provoking science fiction is when the alien Eros upbraids the human characters for not using "the mind God gave you".
Jeff: You talk of God!?
Eros: Do you think it impossible that we, too, might also think of God?
- An old joke has man being chased and cornered by a bear. About to be devoured, he gets in a last prayer asking God to make the bear a Christian (either like him or, in a variant where the man is an atheist, as a compromise after God asks why, exactly, He would be required to intervene in favor of someone who denied His existence all his life). The bear suddenly sits up, puts its hands together, and says "Lord, I thank you for this meal you have provided."
- Anne Rice has her vampires doing things like going into churches and cathedrals and praying - trying to work out their inner conflicts as to whether they are genuinely evil, or if any good remains, or if they have advanced beyond human dichotomies such as the good-evil thing. In the Rice universe, her vampires can handle crucifixes and holy water without ill-effects and can even encounter Angels and not be adversely affected.
- Baudolino: Not only are all the various monsters in Deacon John's kingdom all Christians, each species has its own interpretation of Catholicism and refuses to consider the others as anything but heretics (parodying the many, many schisms the religion has experienced over time), which screws them over during the final battle.
- Blood Books, by Tanya Huff, prominently features a vampire named Henry Fitzroy who happens to be a practicing Catholic, and was actually alive during the Protestant Reformation. Naturally crucifixes have no effect on him or other vampires.
- Known Space has the Kzinti, a mainly antagonistic alien Cat Folk who chiefly worship their own Fanged God; one Kzinti religious sect, the Kdaptists, however believes that God made man (i.e. humans) in His own image (and that that's why humans regularly win every war the Kzinti wage against them).
- In "Nine Yards of Other Cloth", one of the Silver John stories, John explores Hosea's Hollow, a valley that's reputed to be haunted by a terrifying man-eating monster. A local legend tells of a man named Hosea Palmer who went into the hollow to deal with the monster; after that, the monster never raided beyond the hollow, but Hosea Palmer was never seen again. In the hollow, John finds an old grave, with a wooden marker inscribed by an unknown hand with Hosea Palmer's name, and eventually learns that Hosea befriended the monster and gave it religion, and the monster buried him when he died.
- Andromeda: Wayism, a Buddhist-like cult of pacifism and universal harmony, is followed by some of the Magog race, which are otherwise Always Chaotic Evil. One of the original main characters is a Magog Wayist named Rev Bem.
- In Supernatural, some demons are Christian, or at least implied to be, because, you know, their war with angels is quite a big proof of the fact that Christians were right in at least a few things. There's also a Christian group of werewolves in one episode.
- Dungeons & Dragons: In the adventure Knight of the Living Dead, the protagonist is a human worshiper of the Forgotten Realms deity Torm. He dies and is brought back as an undead, which are normally Evil. He still has the capacity for Good inside him and, if he succeeds in his mission to stop an evil plot, Torm may bring him back to life.
- GURPS: The GURPS Banestorm setting has humans from medieval Earth and many other races from other worlds all being brought together in a magical world. This has lead to things like Orc tribes adopting the religion of their human neighbors, usually Islam or Christianity.
- In Nightlife, the leader of the pro-Human faction of monsters, Golgothanote , is a Christian and wears a cross (usually kept hidden to avoid hurting his fellow monsters).
- Pathfinder: In one of the comics, Kyra, the iconic Cleric character, gets the party out of a fight against an otyugh, a giant, tentacled, sewer-dwelling filth-eating monster, by talking it down once she realizes it's an intelligent being and converting it to the worship of her goddess, Sarenrae.
- Warhammer 40,000:
- The series has the Unfleshed, grotesque, skinless mutants created as a result of a Chaos Space Marine experiment gone wrong, who are very devoted to the God-Emperor.
- In early editions, both Ogryn and Beastmen could serve in the Imperial Guard, with the Ogryns having unshakeable childlike faith in the Emperor while the Beastmen saw their service to Him as penance for being mutants. In recent editions, only Ogryns are still used, still as devout as ever (when Ogryn end up serving Chaos, it's usually a matter of telling them the other side has made the Emperor angry).
- The Elf god Khaine is worshiped as a War God by the High Elves as a paragon of martial honor and valor. The Dark Elves worship Khaine as well... as a vicious god of murder and cruelty.
- Vampire: The Requiem has the Lancea et Sanctum, a group of Judeo-Christian (and Islamic) vampires, some of whom only come into the faith after having died. You'd think their faith might make them kinder, but nope. They see themselves as playing the black hats in God's plan, punishing humanity and basically being the "stick" to keep people good. Basically every negative organized religion trope applies, except for the organist ones. Those are taken up by the Circle of the Crone, the bloody cult following vampires. Among their few redeeming traits is they do at least try to encourage piety and faith in mortals, but they tend to get too dogmatic or cruel over the decades.
- Darkest Dungeon: For a given value of "monster", the Abomination hero, who is a sort of demon-werewolf-Dr. Jekyll/Mr. Hyde kind of thing, has the ability to pray to God for healing. Despite this, all the heroes with the Religious Bruiser subtype refuse to partner with him (at least until the Color of Madness DLC when they realize they're being jerks).
- Felicia is a Cat Girl that was raised in a convent and actually becomes a Roman Catholic nun in the third game's ending.
- Donovan Blaine doesn't look like a monster at first, but he is actually a half-vampire who holds back a terrible dark side. This is why he became a Buddhist monk to control himself.
- Deltarune has the minor NPC Father Alvin, a winged griffin-turtle kind of creature who is the pastor at the town's church
- In Shin Megami Tensei, all the Law demons are this. When YHWH came to power, he demanded all demons serve him. Those who agreed became angels (Law). Those that refused or were neutral remained demons.
- In Sword of the Stars, the Tarka apparently have a psychological need to beleive in a higher power, and once they met Mankind, they converted to Catholicism.
- In Tales of the Questor, the swamp-dwelling gragum would like to be this, but everyone who's come to them or even risen among them claiming to be godly were actually just charlatans using ordinary magic to simulate miracles. The newly arrived Brother Linnaeus might have better luck, being unable to use any magic and thus provably limited to argument and honest faith.