An increasingly common phenomenon where mythical creatures traditionally feared and shunned, especially such horror staples as vampires, werewolves and demons, somehow become the targets of sexual desires. It's like All Girls Want Bad Boys taken to absurd levels.
Positive attributes of these creatures will be exaggerated, if not fabricated out of whole cloth, and negative aspects will be reduced or removed entirely. Yet often as not, these now romantically inclined monsters will retain their definitive characteristics—such as the fact that they must prey on humans to survive, derive power from suffering, or are just plain evil.
Most often this is seen in erotic romance novels, or their counterparts in other media. The main character will be an ordinary woman, the better for the reader to relate to her, and the love interest may be anything from an ordinary man with a monstrous curse to a ravenous werewolf, bloodthirsty vampire or even a cruel and inhumane demon. At first, said monster will regard the woman as either a nuisance or an actual prey item, but through The Power of Love, she will persevere and manage to transform him into a Bowdlerised version of the source myth, perhaps retaining some rough edges but otherwise a relatively decent being.
This phenomenon has been around, especially applying to vampires, for quite a long time, making this Older Than They Think for people assuming this to be only a recent phenomenon. Also, considering some particular forms of mythology such as Horny Devils and the number of god/mortal pairings in Classical mythology, this attraction to the exotically dangerous may simply be an endemic part of human thought, and reflected in stories throughout history.
Double Standards may apply, but this seems to happen mainly with human women and masculine beasties. On the other hand, see Cute Monster Girl.
Related to Vampires Are Sex Gods, Villain Decay, Bishounen Line, Horny Devils, Interspecies Romance and The Taming Of The Grue. For fanbase attraction to a monster or Big Bad, see Rule 34 and Draco in Leather Pants. Compare Shapeshifting Seducer. Ultimately followed by I Can Change My Beloved in most cases.
Ryuuko Konuma of Wolf Guy - Wolfen Crest certainly believes this trope, though instead of liking the protagonist's more positive traits, she actively hopes he is the most evil and violent thing that ever lived... and is disappointed when she finds out he isn't. And is turned back on when she learns that while not evil or outright violent, he's STILL the most powerful thing walking.
The premise of the My Boyfriend Is A Monster graphic novel series, which features sexy zombies, vampires, fairies, ghosts, and Frankenstein monsters.
In The Unwritten, after Richie Savoy gets turned into a vampire, he apparently has lots of sex with gothy vampire groupies. (Helped along by the fact that he's outed himself as a vampire in a bestselling book.)
The BBC documentary The Human Animal actually explains part of the reason this trope exists as well as All Girls Want Bad Boys AND I Can Change My Beloved in simple biological terms. The short of it is that the dangerous aspects of the target are sexual advertizements. According to the documentary, on a biological level, women are looking for signs of protective prowess. Displays of aggressive behavior are then read as signs of this prowess the same as the physical sign of broad shoulders in males (cultural signs of this vary greatly, but the intended messages are the same). Once partnered up, however, the female will actively work to prevent the male from displaying further (the 'taming' aspect of this trope), so as to prevent the male from gathering further attention from the opposite sex. There's a lot more to human courtship, of course, mostly because unlike other primates alive today, sex among humans lasts more than 8 seconds (usually).
In Teen Wolf, Scott instantly becomes popular with the ladies when he starts turning in a werewolf. People aren't as interested in him when he's not furry.
In Wolf, Jack Nicholson's cuckolded and emasculated newspaper editor gets bitten by a werewolf and becomes more self-confident and sexually aggressive as he turns.
The Underworld series presents most of its vampires as sleek and stylish figures. Werewolves seem to be all male, and are brawny, hairy types in leather. Each film features a romance between the races.
Genderflipped in Ginger Snaps; just before her final horrific metamorphosis, Ginger attends a Halloween party. She is treated as downright sexy because the party-goers mistake it for a costume.
Even zombies are getting into the act with the 2013 zom-com Warm Bodies.
Twilight and its movie adaptations, as everyone even casually familiar with the series knows.
The series downplays or eliminates almost any negative trait that could be associated with a vampire. Part of this is because Meyer was not interested at all in vampires until having a dream that inspired the series (or so she claims) and she intentionally ignored earlier vampire "traditions" in favor of coming up with something she found unique. Which, oddly enough, took more from Mormon Angelic lore than anything else.
While the werewolves are considered the protectors of people in the series, one still ought to not dismiss the dangers of being romantically involved with one, mostly because anger and stress can trigger a transformation. This was proven nicely by Emily, who refused Sam's advances and led him to shape-shifting too close and slashing up her face. They get engagedanyway.
Gothic and Romantic literature tended to have quite sexy monsters. As Victorian England was a sexually repressed society, writers would often link sexuality with the dark and forbidden. Creating metaphorically sexual monsters was also a way of Getting Crap Past the Radar.
Lord Ruthven, of the short story The Vampyre. Lord Ruthven is a seductive figure and is considered one of the first literary vampires. The idea for the story was conceived on the same occasion as Frankenstein by one of Lord Byron's lesser-known friends.
Varney the Vampire, from the gothic horror novel by James Malcolm Rymer. The story is perhaps the first to treat a vampire sympathetically.
Geraldine from Christabel by Samuel Coleridge is another erotic Lesbian Vampire who preys on a woman.
The Bride of Corinth, featuring the first female vampire with a male victim.
Matilda from The Monk is not a vampire, but an agent of Satan who helps the title monk into damnation through her seductive powers.
Dracula is a mixed case. In the original book, Dracula is a rather ugly old man who preys on young women, making him more of a monstrous pervert at the start; however, he becomes younger and better looking with the more victims that he feeds on. In later adaptations, Dracula is often transformed into a suave, sophisticated, exotic, and darkly seductive presence. Dracula's vampire wives, however, are attractive even in the original novel.
In his Danse Macabre, Stephen King discusses the sexuality within Dracula at some length, saying that the novel "fairly pants with sexual energy". He points out that Lucy's reaction to being bitten by Dracula—sighing, moaning, and writhing—is Bram Stoker's "classy" way of telling us that she's having a mind-blowing orgasm.
The Sookie Stackhouse Mysteries series is built on this trope, with vampires. There's even a special term for people who like to have sex with vampires: "fangbangers".
A group of youngsters were into the whole Vampires Are Sex Gods thing until the vamps came and started killing everyone.
Angel, Spike, Darla, and possibly Oz seem to apply. Not to mention Dracula. And who can forget vampire Willow and Xander?
The first episode had Jesse become suddenly more confident and charismatic after becoming a vampire. Joss Whedon acknowledges the use of this trope on the DVD commentary.
Xander considers himself a romantic demon magnet; he's had relationships/attractions with at least three supernatural creatures, not to mention losing his virginity to a vampire slayer.
True Blood lives and breathes on this trope. Everyone should have sex with a vampire at least once. And you should see the werewolves and shapeshifters.
The Vampire Diaries (as well as the book series that inspired it), as you might guess from the name, is also built on this trope. By the third season, every surviving member of the main cast has had a relationship (or several) with a vampire, except for one. Who is a witch whose mother becomes a vampire.
As a long-running series dealing with, well, the supernatural, Supernatural has touched on this trope. Sam's girlfriends have included a werewolf and a demon; he's also had romantic friendships with a vampire and a kitsune. Dean has generally avoided relationships with monsters; angels,on theother hand...
Sound Horizon teaches us all a valuable but often overlooked lesson in Seisen no Iberia: Hooking up with a demon is a pretty sweet deal (or at least a much better deal than most Sound Horizon albums), religious heresy be damned.
Done with Gill Man (a.k.a. The Creature from the Black Lagoon) in Monster Bash.
Woman: "Wrap your flippers around me, fish-boy!"
Played with in Magic: The Gathering, specially in Innistrad. Vampires, while not always evil, are generally selfish creatures with sadistic tendencies and that hunt for sport. However, their aristocratic sophistication and appreciation of art and refined pleasures makes them the target of fascination for many innistradi humans. If the humans end up as vampires, however, they find that the sophistication comes after learning to control their bloodlust. Until then they go crazy at the first whiff of blood. Werewolves, on the other hand, are consistently feared, as they are mindless killing machines.
Changeling: The Lost: The advantage for being part of the Beast seeming is that "animal magnetism" is no longer just an expression - you gain bonuses on social rolls.
Desco: L-look at all these handsome devils! This is bad! Like, totally really bad! Big Sis is at just that age... How could they not make Big Sis's heart throb!?
Fuka: Um, no.
The vampire variant is parodied in the Sluggy FreelanceB Side Comic "Sampire". Sam tries hitting on a girl, she rejects him for being gross and creepy, then he tells her he's a real vampire. She sighs, and suggests they go make out in an alley. Sam in general is a great big subversion of this trope, being a vampire Casanova Wannabe.
Also frequent at Renderoticanote less worksafe than anything else listed on TV Tropes — Google it if so inclined. Including everything but not limited to the creatures listed in the above article.
If you see a sexy werewolf online 9 times out of 10, the artist is usually a member of the Furry Fandom, since, well, it isn't exactly a stretch for a person who's attracted to anthropomorphic creatures to like what is, essentially, an anthropomorphic creature.