Nonhuman Lover Reveal

A boy meets a girl of his dreams, falls in love with her, is reciprocated, and all seems shiny... until The Reveal that the girl isn't quite compatible with him biologically. For example, she is an alien. Or a ghost. Or a demon. Or a six-foot praying mantis in a person-suit. Or... Either way, she is not human and that's a slight hindrance in their relationship. How exactly it plays out depends largely on the author:


 * The Power of Love rules supreme and Interspecies Romance ensues;
 * They are forced to part ways despite still loving each other;
 * She offers him to make him just like her and he agrees (very common for vampires);
 * Occasionally, this is done to save his life via an Emergency Transformation; the relationship may or may not survive this act.
 * Alternately, he manages to purify her, assuming her condition is reversible and seen as bad. A Cute Ghost Girl might find her body in coma state in hospital. God may "punish" an angel by turning her into mundane human.
 * One of them just can't get over it and breaks up.

Gender Flipped (completely or partly) variations are also included.

If they stay together, Half Human Hybrids may result.

Obviously involves Interspecies Romance. May be a case of Magical Girlfriend or even Action Girlfriend. A common trope in Paranormal Romance but it appears in other genres as well.

Anime and Manga

 * FLCL: Boy meets a girl who eventually turns out to be an alien. Alien seduces boy, uses him, then tosses him away.
 * Eureka Seven: Boy meets alien.
 * Baccano: Boy meets immortal, borderline-asexual homunculus.
 * Chrono Crusade: Girl meets demon.
 * From Vampire Knight, we have Yuki, a human, falling in love with the vampire Kaname. All the students at the Night School are secretly vampires.
 * Mermaid Melody Pichi Pichi Pitch has an inversion (mermaid meets boy), The other members of the Power Trio, also mermaids, get human love interests as well; the manga makes it more clear that they'll probably end up Star-Crossed Lovers because of this, but the anime ends on a happier note. Finally, the series' backstory includes other stories of boy-meets-mermaid played straight; one is a legend with an ambiguous ending, but the other... didn't end well.
 * Blue Submarine No. 6 Man meets mermaid/catgirl hybrid with similarly ambiguous bittersweet ending.
 * Mahou Sensei Negima: Boy meets all of the above.
 * Asobi Ni Iku Yo: Boy meets Catgirl Alien, knows a Half Alien.
 * Otome Youkai Zakuro: Men meet Hanyou Girls
 * Tasogare Otome X Amnesia: Teiichi doesn't realize Yuuko is a ghost when he first meets her.
 * Dragon Crisis: Boy meets Dragons and a Half-wolf girl.
 * Yumekui Merry: Boy meets Dream Demon.
 * Fruits Basket. Girl meets boy(s) who turn to have a secret, magical association with the signs of the Chinese Zodiac, and turn into total animals whenever they're hugged by a member of the opposite sex.
 * Fractale: Boy meets Doppel and a.
 * Dragonaut the Resonance: Boy meets giant, alien dragon.

Fanworks

 * Novembersmith's RPS fan-novel The Anatomy of a Fall has boy meets ghost, with a fairly beautiful reveal around the middle of the fic.
 * Gender Flipped in 'Shadows Of The Past' as when they were dating.

Film

 * Original Underworld: Boy meets vampire.
 * The Tales From the Darkside movie has a Downer Ending version of this. Guy finds out his wife is a gargoyle, after telling the tale of seeing one once, and promising never to speak of it.
 * Splash: A variation on the classic mermaid-falls-in-love-with-a-human story; she can appear fully human unless she gets wet, which comes as quite a surprise to him the first time it happens.
 * Let the Right One In. A dark puppy-love version. A Boy meets a mysterious girl and makes friends with her, only to discover, later, that she's a vampire responsible for a series local murders.
 * The 2010 remake Let Me In has the same.
 * The Deaths of Ian Stone has a peculiar relationship to this trope. In the very beginning, everyone in the setting seems clearly human or clearly inhuman.
 * Galaxy Quest. Fred Kwan and Lailari, who he thinks is a Human Alien. He's quite wrong. But he doesn't care.
 * The Man Who Fell to Earth gender flips and deconstructs this with alien Thomas Jerome Newton and his Earthly mistress Mary-Lou. They actually consummate their relationship before he reveals his true, Rubber Forehead Alien form to her. Once he does, their already-troubled relationship is only further damaged -- out of his disguise, he's not capable of lovemaking in the human manner, and she finds him physically hideous anyway.
 * The Bermuda Depths: Magnus and Jennie, servant of a sea demon.

Folk Lore

 * There's a Japanese myth about Yuki-Onna, with the same plot as the Tales From the Darkside movie above.
 * Older Than Print: Kitsune are subject to this trope. Kitsune-wives usually left when their true nature was exposed, but in at least one tale, the husband called after her, reassuring her of welcome, so she returned, but only at night.
 * The Selkie myths of Ireland, almost exactly the same as the kitsune-wives, but the men capture the women by hiding the pelts that let them turn back into seals.
 * The Huldra women of Norwegian folklore become mortal and gain souls when they are married to a man. However, they still keep their magic and freakish strength, much to the peril of unfaithful husbands.
 * Subverted in an Arab folktale. A daughter of a ghoul (human-eating monster) winds up with some of its magical powers. She nearly gets married to a prince except for the presence of another girl. She throws herself into an oven and reforms, leaving fresh bread ready in the oven to start a welcoming feast for the prince. The other girl claims similar abilities, throws herself into the oven, and burns to death.

Literature

 * Twilight: Girl meets vampire.
 * Marion Zimmer Bradley's The Wild One: Boy meets.
 * Discworld: Dwarf-raised human boy tall dwarf meets werewolf.
 * All The Sookie Stackhouse Mysteries, where girl meets vampire, werewolf, were-tiger, etc.
 * Let the Right One In: as with the movie, a young boy meets a strange girl, and an innocent childhood romance develops, before he discovers that she's a bloodthirsty vampire.
 * Blood and Chocolate: Boy meets werewolf. One of the more cynical cases, as
 * Light Novel Haiyore! Nyarko-san takes this to a comparative extreme: boy meets Nyarlathotep.
 * Harlan Ellison has a short story called "She's A Young Thing And Cannot Leave Her Mother" where boy meets (a.k.a. "Camilla").
 * The Door Into Fire: Boy meets fire elemental.
 * The Gravesavers by Canadian author Sheree Fitch had a girl meet a boy, who
 * In Philip Jose Farmer The Lovers a man from an oppressive puritan theocracy meets the girl of his dreams in another planet. Except that she's actually a lalitha.

Live Action TV

 * Night Gallery, a show famous for its twist endings, liked this one.
 * "The Phantom Farmhouse": she's a werewolf who's actually a ghost.
 * "Lindemann's Catch": she's a mermaid.
 * "The Girl With the Hungry Eyes": she's a psychic vampire.
 * "Death on a Barge": she's a regular vampire.
 * Isabel in Roswell married Jesse Ramirez, who was human, but he didn't find out Isabel was an alien until later in season 3.
 * Big Wolf On Campus in the second season has this. Human girl Lori Baxter dates werewolf Tommy Dawkins. However, towards the end of the season,
 * The main character of Moonlight was turned into a vampire by his wife on their wedding night, who forgot to run it by him first before doing so.
 * True Blood has Tara and Sam, human meets shifter.
 * Being Human has werewolf George fall in love with regular human Nina.
 * In Season 2, ghost Annie goes on a date with human Saul, and seemed to have feeling towards normal human Hugh. Also vampire Mitchell is falling for regular human Lucy.
 * Star Trek 'verse: Boy meets android, or hologram, or Leanansidhe IN SPACE, or astral projection of someone else's subconscious self, or dead Red Shirt with instincts of aliens who resurrected her, or long dead to stay and the messages to each other are going through a time warp, or woman whose presence will erase bits of your memory relating to her once she's out of sight... the list goes on. The girls' dating lives are no easier, just not featured quite as often.
 * Subverted in Buffy the Vampire Slayer: Tara thinks she's a demon and goes to considerable length to prevent Willow from finding out. Turns out she's not - it was just part of her abusive family's "spin to keep the ladies in line".
 * Played straight in the season one episode Teacher's Pet where Xander gets a crush on a substitute teacher
 * And when Buffy discovers that
 * And again with Xander when he falls for the Inca Mummy Girl
 * Possibly a third time in season seven when he meets a nice girl who
 * While he knew Anya was an ex-vengeance demon at the start of the relationship - it was a while before he discovered what vengeance demons actually look like.
 * Played with extensively in Season 4: Riley discovers Buffy is the slayer (which means demon infused) as she discovers he is a superagent (which is ultimately revealed to be a little bionic).
 * Charmed: Mid-way through series 1 it's revealed that Piper's (then) boyfriend Leo is not human and that he's a whitelighter. There had been a few comedic suspicions about him prior to the reveal due to Piper's bad luck with men (her boyfriends often ended up being revealed as evil warlocks) but the reveal that he's their guardian angel does come as a shock to all of them. Since whitelighter/witch romances are traditionally forbidden, the couple do spend most of the entire eight seasons struggling to make it work before everything finally works out in the end. Subverted in that whitelighters are actually born human but are transformed into whitelighters and can be turned back into humans if the occasion demands. All three of their children are half-whitelighter, half-witch.

Video Games

 * There was a subplot in the Game Boy Advance RPG Robopon 2 based around this. You have to round up a group of alien schoolgirls on a field trip from the moon (It Makes Sense in Context) and one of them disguises herself as a human and has a guy fall in love with her. You chase them all over the world map. When she finally admits to him that she's an alien, he says that he'll love her no matter what.
 * Fate Stay Night: Boy meets superpowered ghost of . Boy meets superpowered magus. Boy meets.
 * This is one of the possible endings in the Interactive Fiction game Afflicted, where you are a restaurant inspector . After the player   if you simply leave Nikolai's Bar afterwards,.
 * Fire Emblem: Blazing Sword: Boy meets.
 * Fire Emblem: Path of Radiance: Boy meets cat(girl) in his backstory.
 * Saya no Uta: Boy meets.
 * Disgaea 2: Boy meets demon. Turns out to be a non-issue since Disgaea 1 already showed that human/demon Half Human Hybrids are possible (and for those who haven't played it, a character from that game explains it anyhow). . Of course, by that point, it's stopped being "boy meets demon" and started being "boy meets ."
 * Demonbane: Boy meet Moe Personification of Necronomicon.

Webcomics

 * Ow My Sanity, explicitly a deconstruction of the Magical Girlfriend genre, pairs a human with a Humanoid Abomination. The strip is ongoing, but it looks like said human is going to get an Unwanted Harem composed entirely of Lovecraftian monstrosities.
 * Xkcd has this comic, where the reveal shows unexpected dangers of online dating.

Web Original

 * Dept Heaven Apocrypha: Girl meets demon.
 * Kumiko the Demon Girl: Boy meets Succubus.
 * The Monster Girl Encyclopedia: Varies. Several monster girls can disguise themselves really well. Among those, there are some monsters whose will just have fun with male humans, other will seek romantic relationship with their husbands though.