Interspecies Romance/Literature

"Mickey Finn (A 6'11'' tall, 600 pound robot/cyborg alien) "You do not even know if we are sexually compatible--"
 * The One Who Waited, Alice and the Boogeyman, who is a kind of shadow-monster.
 * Sgt. Bill Booley and Windsweet from Legion of the Damned. Booley is a member of a futuristic Foreign Legion, while Windsweet is a Naa, a cat-like humanoid alien. Booley is taken prisoner by Windsweet’s tribe, romances her, kills her abusive suitor in an ‘honor duel’ and consummates the relationship before escaping the village with the help of the humiliated chieftain, Windsweet’s father. Before the end of the book the two will unite the humans and Naa against far less friendly reptilian aliens and conceive a son. Their hybrid son continues the family tradition by romancing human and Naa alike.
 * Wet Goddess: Recollections of a Dolphin Lover: nuff said
 * Piers Anthony seems rather fond of this trope.
 * Particularly Squick-inducing pairings are hinted at but not shown explicitly in Xanth, where any two creatures of opposite gender who drink at a "love spring" will fall in lust and (successfully) interbreed. This is the origin of most of the sentient species in the series including harpies (human/vulture), centaurs, etc. We also have a story where an ogre/human hybrid falls in love with a human/nymph crossbreed, the child of a centaur/hippogryph (eagle/horse hybrid) and all manner of others.
 * In Xanth, EVERYTHING is intelligent (at least to some degree), though not everything can communicate in the human tongue. And in all fairness, Biology is not at all involved. Babies literally arrive via the stork, so there's less squick than it seems.
 * However, there's the process of summoning the stork...
 * In his Apprentice Adept novels, we are "treated" to human/unicorn (the unicorns can shapeshift to human), human/robot, human/werewolf, human/vampire, and human/alien relationships, just to name a few.
 * Incarnations of Immortality series: human/ghost, human/demoness (three times, one rather Squicky), human/damned soul. Zane/Luna is an aversion, as they're both human (though he's the current Death).
 * Girl falls in love with robot is a key element in Isaac Asimov's The Robots of Dawn.
 * Philip José Farmer's was famous for writing one of the first erotic stories between a human and an alien in The Lovers... If you can really call that "erotic."
 * In The Firebringer Trilogy, what was probably intended as simply a powerful friendship betweem the unicorn princess Lell and the gryphon warrior Illishar seems to be a bit more than that at times...
 * Alan Dean Foster's books.
 * Quozl is about cute rabbit-like aliens who eventually integrate into human society, and believe in frequent sex anytime, anywhere with any compatible intelligent species as a legitimate means of blowing off steam. The book establishes that once Humanity understood that social more, the Quozl quickly become very popular company. On the other hand, humankind was the only other intelligent species they'd run into.
 * Spellsinger is set in a world where humans and anthropomorphic animals live side by side including romantic and sexual encounters. Subverted in that, while the Earth-import protagonist feels attracted to an ermine stripper, he's dismayed by his own feelings and never actually goes native enough to join in this trope's fun.
 * The Humanx Commonwealth series features a wide variety of alien species. Most of the time the biological and social incompatibilities are treated seriously, although mental compatibility between some humans and the insectoid Thranx occasionally reaches Ho Yay proportions. There are some memorable scenes in Bloodhype, however, where a particularly flirty character discusses ways to erotically stimulate members of other species, intentionally and quite successfully Squicking out her companions. Better Than It Sounds.
 * In Sliding Scales a reptilian AA'nn falls in love with the protagonist Flinx.
 * Played in an unusual fashion in The Dark Tower, where Roland has sex with a Succubus in order to get information from it. In a later novel, the same succubus, now in male form, rapes Susannah and impregnates her with Roland's sperm. When the resulting child is born, it's a cannibalistic human-spider hybrid. This is exactly how medieval folklore said succubi/incubi worked. That a demon could never create true sperm or truly mate with a human, so demon children were the result of a succubus stealing a man's seed, turning into an incubus and raping a woman. Succubi/incubi themselves have no "real" gender, being spirits. Also, Rhea and her snake...
 * Mercedes Lackey's The Eagle and the Nightingale, with human/birdman relations (along with, "Oh, yeah, people do this all the time back home.").
 * The Fire Rose deals with the romance between a human and an anthro wolf.
 * Brightly Burning contains a "lifebond" between a human and his intelligent but non-anthropomorphic horse. Thankfully, the author avoids discussing sex.
 * The Obsidian Trilogy has Idalia (a human) in love with Jarayan (an elf).
 * The Silver Metal Lover, by Tanith Lee, and its sequel, Metallic Love, in which, you guessed it, girl falls in love with robot.
 * Fritz Leiber's novel Wanderer included romance with an off-world female from a feline race. Think serious scratches down the back. Leiber's Fafhrd and The Gray Mouser have non-human girlfriends among their conquests, including a ghoul and a sapient rat-girl.
 * Deconstructed in several H.P. Lovecraft stories that show how squicky such a thing would actually be - eg. Facts Concerning the Late Arthur Jermyn and His Family and The Shadow over Innsmouth. On the other hand, considering Lovecraft's peculiar attitude towards intraspecies romance, they could also be seen as not so much a Deconstruction but just a different brand of Fantastic Racism allegory... Let's face it: the guy was squicked out when he discovered that his great, great grandmother was Welsh. In a way, this could be seen as a real-life deconstruction of Squick itself.
 * Perdido Street Station by China Mieville: The main character's lover is an insect-woman. Admittedly, she does just have a big insect in place of a head; everything else is human.
 * Sometimes you get interspecies sex without the romance, e.g. Rishathra in Larry Niven's Ringworld series (it's a bonding/peace ritual between hominid species).
 * Averted with species that are too different, however. The marooned kzinti Chmeee eventually had to invade the Map of Kzin in order to score.
 * Niven also discusses interspecies sex in the short story "Shall We Indulge in Rishathra?", found (along with the Superman essay, mentioned above) in the short story collection N-Space.
 * The Draco Tavern series contributes to the subject in the short story "Breeding Maze". Arguably, another story from that setting, "Smut Talk", also counts, as it explores the possibility of a sexually transmitted Alien Invasion.
 * Eragon falls madly in love with Arya, an elven ambassador. Lots of Love Hurts ensue.
 * Carrot and Angua of Discworld (conspicuously tall and clean-shaven dwarf [by adoption; biologically human]/werewolf). And don't forget Angua's implied past relationship in the  The Fifth Elephant with an ordinary, albeit extremely clever wolf. She's also been hit on (albeit unsuccessfully) by dogs, including Gaspode the Wonder Dog and Mr. Fusspot. The possibility of her and Carrot having children is a plot point in Feet of Clay.
 * Said wolf himself was the distant descendent of such a union, at least according to Angua.
 * Suspected to be. She thinks one of his ancestors was a yennork, a werewolf stuck permanently as either a human or a wolf (in this case, as a wolf).
 * Lupine and Ludmilla Cake: While they're more-or-less the same thing (werewolves), one's a wolf who turns into a wolf-man during the full moon, and the other is a human that turns into a wolf-woman (they more or less meet in the middle). Somehow, they make the relationship work, despite only having one week-in-four per month in which they are the same bodyshape. The secret and beloved dark heart of this meme is that that's very much their affair, and none of our business... or to put it another way, maybe they are happier than you think.
 * There's also pretty heavily implied human/vampire in the form of Lord Vetinari and Lady Margolotta. (Though there is debate on how far it went given some fans' opinion that a guy that finds people playing instruments as a bit overly-physical would view doing it as pretty damn gross.)
 * Then again, Vetinari subverts readers' expectations and in-story rumors left and right, and you never know which it'll be.
 * It's mentioned in Lords and Ladies that there are some half-elves around, and Imp y Celyn in Soul Music is said to look a bit Elvish (though this last is a mostly a punning reference to Elvis Presley).
 * It's also been stated (or at least implied) that Nanny Ogg has some dwarfish ancestry, albeit several generations back.
 * There's also the town whose inhabitants are remarkably short and ill-tempered due to a powerful being who couldn't spell causing everything the King touched to turn to Glod--Glod being a dwarf from the nearby mountains who found himself dragged from his home and duplicated dozens of times.
 * Casanunda will romance (or at least boff) any female who'll hold still long enough, pretty much regardless of species.
 * In Snuff, there is a one-page mention that a dwarf and a troll have set up a house together in Ankh-Morpork.
 * The same book also has Nobby Nobbs becoming the idol of adoration for a female goblin, and he starts reciprocating. Not quite as suprirising as one may think, given that Nobby is so damn ugly for a human that many people are probably more likely to assume he is a goblin at first glance, and for a long while the closest thing Nobby had to a girlfriend was a girl who was so crosseyed she was nicknamed "Hammerhead" (as in the shark) and the relationship basically consisted of her angrily throwing fish at him when he came near her.
 * Unseen Academicals has a romance between Glenda (human woman) and Mr. Nutt (male orc), as well as a (possible) homosexual relationship between a human male and a dwarf.
 * Many of the girls of Harry Potter were quite taken with Firenze. Hagrid's father also apparently produced a child (namely Hagrid) with a female giant, and Flitwick has a goblin among his ancestors, but since these are kid-friendly novels none of these scenarios actually occur on "camera".
 * There's also Fleur, who has a veela grandmother and who marries full-blooded human Bill.
 * Don't forget Remus Lupin, a werewolf, and Nymphadora Tonks.
 * Though werewolves were not considered a different species, lycanthropy in the Harry Potter universe is more like AIDS.
 * Actually, werewolves have beast/being status in the wizarding world, so it's just as fair to call them a different species as it is to call giants and veelas different species.
 * Teased in The Demon Awakens, the first of R.A. Salvatore's novels set in his own world of Corona. A centaur comments that he'd only let a woman ride him - and only if he got a ride himself afterwards.
 * Subverted slightly in Wild Cards wherein there was a human/centaur sexual relationship. The subversion comes from the fact that Finn the Centaur was once entirely human, but the Wild Card virus turned him into a centaur. Brain Trust/Tachyon [human/Takisian], plus Tachyon also had many other relationships with human women, including one which resulted in Half-Human Hybrid child (mentioned as deceased) and grandchild. Popinjay also had a Takisian wife. Then again, Takisians are essentially human.
 * The Star Wars Expanded Universe tends to feature this trope a lot:
 * Several interspecies romances factor into Michael Stackpole's and Aaron Allston's Rogue Squadron and Wraith Squadron series.
 * The most prominent are Gavin (Human) and Asyr (Bothan), who catch quite a lot of flak for their romance, what with them being war heroes and all. Interestingly, it's the Bothan who catches most of this--even though a prominent Bothan politician notes to her that xenophilia isn't unknown among Bothans. It's just that she wants to stay together long term and adopt children - the parts match up, but they can't reproduce.
 * One of the more memorable examples, played for laughs and occurring off-screen in the past, was the romance between Corran Horn (Human) and a ferret-like Selonian. A quirk of Corran's bio-chemistry made his sweat acidic enough to penetrate the waterproof fur of his Selonian lover and irritate her skin, while her fur had a similar effect on his own; they effectively sunburned each other whenever they touched. Corran also brings up the point that dating outside of your species can be problematic in other ways - what if your partner is used to giving and receiving love bites? With ten-centimeter teeth? Though thankfully there's no indication that he has personal experience in that particular area.
 * The Wraith Squadron books had a fair share of this, too, with two of the squadron members - one Human, one Twi'lek (the woman, naturally) - getting together
 * In the Rogue Squadron books, there's also a male Twi'lek, Nawar'aven, hooking up with a female human. This being written by Stackpole, it's completely out of focus.
 * Among the Wraiths, the team plays a prank and allows the residents of a seedy bar to think that Piggy (the male Gammorrean, who looks like exactly what you'd expect from the name) and Falynn, a human female, are a couple. They're not, and Piggy gently takes her to task for being embarrassed about being seen with him.
 * Shadows of the Empire also had Xizor seduce Leia. Xizor is a Falleen, a suspiciously mammalian-looking "reptilian" species (EU sources have since retconned them to be "reptomammals") whose members can (and do) produce pheromones that can ensnare a good chunk of the sentient species in the Galaxy.
 * Between the publication of The Thrawn Trilogy (Winter's first appearance) and the X Wing Series (her eventual husband Tycho's introduction), a few Star Wars Expanded Universe novels hinted at White-Haired Pretty Girl Winter Retrac and Admiral Ackbar being an item. Yeah.
 * Star Wars literature in general tends to have a fair amount of Interspecies Romance, and sometimes between rather disturbing couples. One example would be Dice Ibegon and Lak Sivrak, a female Florn Lamproid and a male Shistavanen. The latter looks like a Wolf Man... the former? A snake-like body, six clawed legs, a poisonous sting in the tail, and four long, curving fangs forming a ring around their circular mouth. And the two were explicitly stated to be physically compatible and very much attracted to each other...
 * There are numerous species that are classified as "Near Human". Which basically means by the proper definition of the word, they're not really separate species at all, just humans with minor visual differences (and occasionally a bit more, like the Miraluka, who have no eyes and see through the Force). Given the vast amount of time covered in the EU, it's likely that all the "Near Humans" were descended from regular humans at some point in the distant past. On the other hand, the EU also includes a few romances between humans and distinctly non-human aliens, where it's made clear that they're not capable of reproducing at all.
 * Death Star has two sets. One pairing has no humans in it; it's a Twi'lek woman - who has blue skin and brain tails - and a Zelosian man, a Plant Alien who looks like a human with green eyes and blood. The other pairing looks human, but one of them is actually a Mirialan, an offshoot of humanity.
 * In The Crystal Star, Han Solo met a female Ghostling, a species that is considered, by humans at least, to be incredibly beatiful and apparently most ghostlings feel the same about humans. The problem is that Ghostlings evolved on a planet with almost no physical hardships or predators and are extremely fragile by human standards. According to Han any relationship between a human and a ghostling inevitably ends with the ghostling's death.
 * Piro and Ibronka in the Viscount of Adrilankha. Granted, this one is less obvious due to the characters being of different clans of the same race which were manipulated by extradimensional aliens millions of years in the past to be almost the same but have a few traits resembling the native wildlife of the world instead of actual different species, but the severity of the cultural taboos make this count. There are also Zerika and Laszlo, who are Dragaeran and Easterner, respectively.
 * Being based on a Dungeons and Dragons world (see below), there was a surprising amount of angst from Driz'zt about his eventual romance with Catti-brie - though admittedly only part of that was due to race. It's done with now, and they're married, though Salvatore has said he's not gonna give them kids.
 * It might have had something to do with the fact that he knew her when she was ten years old...and that he's pushing eighty but would live for centuries (barring accident, violence, or disease).
 * The angst was also partially, at least at first, about the part where Cattie-Brie was the love interest of Drizzt's best student Wulfgar before he had a bridge cavern dropped on him when Drizzt became more popular.
 * Contrast him with Jarlaxle, the charmingly evil dark elf rogue, who can and will sleep with anything with two legs, a pulse, and the ability to consent (which is what makes him charmingly evil, not just evil). And maybe female sexual organs. He and Drizzt both are noted to be unusual among drow males, who are culturally xenophobic. (Females will sleep with anything, including demons, in the pursuit of power, though there's probably no romance. For that matter, intraracial relations in traditional/Llothian Drow society are rarely all that romantic.)
 * There's a reason behind the old joke "How the Drow do it? He, she ".
 * Then again, Forgotten Realms got Crinti (aka "Shadow Amazons"), descendants of southern drow, humans, and half- (surface) elves who looks accordingly and got strong drow cultural influences. The people numerous and strong enough to raid every once in a while Halruaa, of all places.
 * Happens in the Animorphs series with two of the main characters, one of whom is a human stuck in the body of a hawk (he regains the ability to temporarily turn back into a human.
 * At least one of the books directly addresses the ambivalence both characters feel about the relationship, including with issues such as Tobias's much shorter lifespan if he stays as a hawk.
 * Actually, Tobias's parents were a human and an Andalite. (A shape-shiftying alien thing). So they could qaulify to. And as Tobias is half-andalite, his relationship with Rachel is interspecies regardless.
 * Also present in the companion books The Andalite Chronicles (Andalite/human) and The Hork-Bajir Chronicles (Andalite/Hork-Bajir. Less squicky than usual due to the Voluntary Shapeshifting technology that allowed them to become members of the same species.
 * Averted in Goddess by Mistake, a light fantasy novel wherein the heroine finds herself in an arranged marriage to a centaur (who takes human shape for the actual coupling).
 * Miles Vorkosigan's on-again/off-again relationship with Taura should count (despite the Absent Aliens setting in the Barrayar Books, she is at least as far from Human as a Drow is). Leo Graf's and Bel Thorne's respective marriages into Quaddie society also apply.
 * In Holly Black's Valiant, Val, a human, is in love with Ravus, a troll.
 * Whose own father was a human, although apparently troll blood always breeds true.
 * Magician: Tomas and Aglaranna (human / elf), plus Nakor and the Dark Queen (she's human, but it's strongly implied that he's not).
 * Tomas was somewhat mutated by being possessed by the Valheru Ashen-Shugar, a survivor of the race who used to own the elves. He stated that his lifespan had been extended to a thousand years.
 * Neil Gaiman's Stardust: Tristran and Yvaine (half-faerie half-human / star, ya rly)
 * Tristran's parents, and Dunstan (faerie / human), obviously. And a side mention of an ordinary cat being knocked up by a faerie cat, producing a smoky blue kitten with color-changing eyes. The other kittens in the same litter were normal, but cats can have kittens by multiple fathers in the same litter.
 * Robert Silverberg's short story "Ishmael In Love" is told from the perspective of a dolphin in love with his (human) trainer.
 * The product of Nira and Jora'h's interspecies romance (and her half-siblings, some of whom are also her cousins, born of the interspecies rape of Nira by Jora'h's brother among others) save the galaxy in Kevin J Anderson's Saga of Seven Suns.
 * Interspecies romance was fairly common and accepted in Alien Nation, although the Tenctonese tended to be fairly rough in sex so had to visit clinics to make sure they took it easy on their human partners. One of the Continuation novels explores the idea of Newcomers and humans interbreeding, but it turns out to be
 * Spider Robinson handles interspecies romance quite logically in "The Blacksmith's Tale" in his Callahan's Place series.

Mary Callahan (Human) "The hell I don't. I can see fingers and a tongue from here; anything else is gravy.""


 * The Firekeeper series presents us with the namesake heroine, Firekeeper, and Blind Seer, a Royal Wolf (bigger than most and possessing a sentient mind). Firekeeper wrestles with these feelings for a while but seems to come to terms with them by the end of the sixth book.
 * Commander Bradshaw of the Thursday Next books is married to Melanie, who's a quite nice woman with conservative taste in dresses, and who also happens to be a six-foot-something gorilla. Bradshaw is rather sensitive about the topic.
 * In the Nursery Crime books by the same author, Ashley, an alien member of the force (who at one point mentions that the type of earth creature his species most resembles are several jellyfish stuffed inside a balloon too small for them) becomes quite taken with Mary, and even manages to take her out on a date that she tries fairly hard to avoid. The end result is oddly sweet.
 * The first book in this series, The Big Over Easy, Humpty Dumpty (a 6 foot tall anthropomorphic egg) has several relationships with women (all of whom claim to be very satisfied).
 * The second book, The Fourth Bear, has Goldilocks having an affair with one of the Three Bears.
 * There's a lot of this in the Twilight books, especially concerning Bella.
 * We also have a multiple-case scenario here, if you remember that:
 * 1) Edward is (up to some point) a living corpse (making Bella suffer from a severe case of Necrophilia in the 4th book and there after)
 * 2) Edward is 117 years old (making him 100 years older than Bella, who is a 17 year old girl at least on the first 3 books).
 * Though by the end of the series, . But then we're told
 * Many of Tom Holt's books feature a character who is really a type of magical being shapeshifted into human form, who fancies a certain human. In Nothing But Blue Skies, the protagonist is a female dragon disguised as a human, who develops a crush on a young human man. The Paul Carpenter series features a she-goblin who shapeshifts into a different beautiful human girl every day and tries to hit on the main character. She mentions that lots of goblin girls like to have flings with humans, and that as shapeshifters, they are open-minded and don't care much about appearances.
 * In JRR Tolkien's Middle-earth legendarium (The Lord of the Rings, etc.) there are several known cases of romances between different peoples, almost all between elves and humans: Melian/Thingol (Maia and elf), Aegnor/Andreth (unhappy Star-Crossed Lovers), Finduilas/Túrin (one-sided), Lúthien/Beren, Idril/Tuor, Arwen/Aragorn (preceding three all married and happy-endish), Mithrellas/Imrazôr (married until she walked out). (Note that Luthien is Melian and Thingol's daughter, and Aragorn and Arwen are both descended from both Beren and Lúthien and Idril and Tuor.)
 * Fandom also has a tendency to pair off Éowyn (human) with Merry (Hobbit). Even though they're both married to people of their own species.
 * There's also Tom Bombadil, an ambiguous "eldest" and Goldberry, a river nymph. Doesn't really matter for the story, though.
 * If you unravel Bombadil's allusions, you can conclude that both Bombadil and Goldberry are Maia, and therefore only any one gender out of habit anyway
 * It's not quite that simple. If you unravel Bombadil's allusions, what you actually conclude is that he doesn't satifactorily fit any of Tolkien's categories as we understand them. It seems as though he was specifically intended to be a mystery.
 * Though unrequited, there's also Gimli's crush on Galadriel, adding dwarfs to the list of races known to fall in love across species.
 * That's courtly love in the best chivalric tradition, though, not romantic love in the "I want to get into your natural-fiber handwoven elvish pants" sense.
 * A short passage in The Hobbit suggests that someone in the Tooks family tree had married into fairy or elven family, which is given as a possible reason for certain hobbits being far more adventurous than the majority.
 * Two words: Lisanne Norman. See also: Sholan Alliance
 * Happens in Amelia Atwater-Rhodes' novels, particularly in Hawksong the first novel of her Kiesha'ra series. To prevent war, an Avian (bird shapeshifter) princess and a Serpiente (snake) prince consent to a political marriage to end their generations-long war, but find themselves falling in love. Their child, a Halfbreed wyvern who represents both her parents' shapeshifting powers, in turn.
 * In her modern day, Nyeusigrube books there are several interspecies romances between vampires, shapeshifters, humans, and sometimes witches, but none are so unusual as Shevaun and Adjila. Shevaun is a vampire and Adjila is a Triste, a particular kind of witch whose blood is almost always poisonous to a vampire. The two species are usually sworn enemies to a point that Triste can be a synonym for vampire hunter. They have been partners for centuries.
 * The main characters in The Owl and the Pussycat. (And in the incomplete, post-posthumously published sequel, they have kids. But this is Edward Lear.)
 * The Dresden Files has a Werewolf/Wolfwere pairing and a human/vampire pairing. A couple was split up when it became a wizard/half-vampire pair. Summer Knight has four changelings, the results of human/fae pairings, although the only background we're told about suggests there's not much romance involved.
 * And let's not forget the other wizard/vampire pairing in the series:
 * Artemis Fowl plays with this trope in Book 6, when kiss and start developing romantic feelings for each other. This is subverted, however, when   discovers that.
 * Subverted? Really?  especially after he , and despite some lingering resentment on her part
 * Continued in The Atlantis Complex where  It's borderline Unresolved Sexual Tension now.
 * Played straight with In fact,  is what causes many events in The Atlantis Complex.
 * The Legend of Little Fur has this as a constant mystery until A Riddle of Green- Little Fur is half elf, half troll. Everyone wonders how an elf and a troll could love each other enough to have a child. The answer:
 * The eponymous heroine Little Fur herself has a mutual Bodyguard Crush with her white cat ally Ginger, who's the feline equivalent of a White-Haired Pretty Boy.
 * In Diane Duane's The Tale of the Five series, the first human protagonist gets involved with a fire elemental, while the second takes up with a dragon. Sex definitely does happen, though it tends to be a complicated sort of out-of-body experience.
 * In the Courts of the Crimson Kings, by S.M. Stirling. After he saves her life, Martian Action Girl Teyud matter-of-a-factly takes Adventurer Archaeologist Jeremy off to her cabin. His human co-worker looks ready to protest (to which Jeremy responds with a big grin and The Bird) but doesn't say anything till afterwards; her main objection being that a bust-up between the two -- likely given the cultural differences between Earth and Mars -- might endanger their mission. A Martian doctor who examines Jeremy later seems rather squicked out by the idea of having sex with a human, even as a simple matter of recreation.
 * Trillian and Zaphod.
 * In the Codex Alera, main character Tavi has tense partnership-turned friendship-turned romance with Proud Warrior Race Girl Kitai. He's human, she's a Marat (basically human, but with enough differences to qualify as a seperate species- white hair, abnormally high body temperature, excellent night vision, and the ability to bond telepathically with animals being chief among them).
 * The animal she bonds with:
 * In Elizabeth Kerner's Song in the Silence series, we have Lanen (human) end up with Ahkor/Varien (dragon). This is facilitated by divine intervention, as
 * Metaplanetary by Tony Daniels (not to be confused with Metaplanetary by S. P. Meeks) pairs a human with an "emancipated" software program. Their kids exist partially in the "real" world and partially in cyberspace simultaneously, and it's mentioned offhandedly that their baby talk was white noise. (There's a Hand Wave about radiation--just go with it.) The intelligent ferret also has a powerful sex drive, which turns towards humans when her original body dies and she winds up Sharing a Body with an Artificial Human, but she's after Anything That Moves, in a rather blunt fashion. (Yes, this book is weird.)
 * Played straight and taken seriously in Ann C. Crispin's Voices of Chaos, where the human female and cat-alien male leads end up in a romantic (and sexual) relationship. Really, considering that it's set in a series whose premise is fostering interspecies understanding and universal goodwill among a cooperative league of friendly alien nations, the only surprise is that it took until the sixth book to do it.
 * In the Mercy Thompson novels, werewolf males typically marry human females. This is because few women opt to become werewolves (or survive the process of becoming one), and because female werewolves in this series almost always miscarry during their change, making them unsuitable mates for males who want to be fathers. Mercy (a coyote shapeshifter) was once courted by a werewolf, who'd sought a fertile mate with similar powers.
 * Mercy herself is the product of a one-night stand between her human mother and a Native American coyote shapeshifter.
 * In the Chanur Novels by C. J. Cherryh we have an instance of this that is somewhat subverted:  falls for   when they are both . When   finds out, she is squicked to the point of.
 * In the Foreigner Novels, we have Bren and Jago his bodyguard sleeping together. Needless to say this was a huge scandal and most just pretend they aren't.
 * Aly (human) and Nawat (crow who could shapeshift into a human) in Trickster's Choice.
 * In Julie Czerneda's Species Imperative trilogy, lampshaded and subverted; one of the alien characters has as his Running Gag happily and frequently teasing the main character, a human woman, about human fictional tendencies in this regard, jokingly accusing her of seeking this very trope, and happily telling her that his species has "No external genitalia". At one point, when he is sleeping, she is tempted to check.
 * Czerneda, a biologist by education, tends to give her alien species differing reproductive systems and/or genitalia.
 * The Belgariad has Belgarath and Poledra (human/wolf, albeit a wolf that is also a sorceress and can take human form), who produced twin daughters Polgara and Beldaran. As well, the Dryads are a One-Gender Race and reproduce with human men. Ce'Nedra is a Dryad and the wife of Belgarion, the hero. Belgarion is a distant descendant of Beldaran.
 * The Darkest Powers series has Chloe Saunders and Derek Souza, the latter of whom is a werewolf. True, Chloe is a necromancer, but for all intents and purposes, she is human.
 * The protagonist of the Garrett, P.I. series has slept with pretty much everything good-looking, humanoid and female, from half-fairy to ghost to demigoddess to space alien ("silver elves"), although he always comes back to Tinne Tate (basically human, perhaps with a bit of elf and/or dwarf blood) in the end. What few species Garrett hasn't bedded, his associate Morley probably has.
 * Subverted in Spar, a 2009 short story by Kij Johnson. After the destruction of her spacecraft, a human woman is trapped in a lifeboat with a Starfish Alien survivor, and they have Squick-inducing Tentacle Sex simply because there's nothing else to do. Worse, she has no means of communicating with the alien, so never discovers if the act has any meaning for it; or even if she's having sex with a sentient alien at all and not just their equivalent of the houseplant.
 * The same author first gain renown with an award-winning 1993 short story, Fox Magic about a romance between a Kitsune and a human, which she later adapted into a novel.
 * In the 1922 novella, Lady Into Fox a British nobleman's wife mysteriously turns into a fox (it's never revealed why), but they continue to live together until she leaves him, because of her now-wild nature. However, she later returns with her children and fox-mate, and they all live together with her ex-husband until she gets killed during a fox hunt and the rest of her family scatter.
 * Also subverted in the short story "And I Woke And Found Me Here On the Cold Hill's Side" by James Tiptree -- humans are driven to have sex with the new and unusual, but in the end receive nothing from the experience except abuse and abandonment.
 * Art and Myrtle Mumby in Philip Reeve's Larklight books are a product of this, to an extent - their mother is a Shaper in a biologically human body, but it's implied that a few things bleed through (like Myrtle's talent for alchemy). Averted with Jack and Ssilissa - only ever one-sided to begin with, and pretty much completely dropped once Myrtle shows up.
 * During The Adventures of Fox Tayle, Fox is helped along on his journey escaping the lab where he was created and the FBI by a handful of sympathetic humans, including Wanda and Diana. Nothing too serious happens, though.
 * Quantum Gravity: Human Cyborg Lila Black gets together with elf Zal.
 * In Sharyn McCrumb's mystery novel, If I'd Killed Him When I Met Him, Miri Malone, who teaches art at a college and creates art with bathtub toys, hires a lawyer so that she'll be allowed to legally marry a dolphin. The lawsuit never gets anywhere, as she decides on a pre-conjugal visit to the dolphin's tank. This proves to be a very bad idea.
 * Mostly played straight in John Varley's Gaea Trilogy, with the Titanide species in particular being (literally!) custom-built for Hot Skitty-On-Wailord Action. Subverted with the Supra variety of angels, which offer sex to human guests as cultural protocol but don't take it any further than a courtship dance and ritualized faux-copulation.
 * Several examples appear in the Mithgar fantasy series. There are several pairings that a reader would somewhat expect (Elf/Human, Mage/Elf) but some others are a bit more suprising:
 * A Dwarf/Human romance is at one point treated as much more taboo than others (largely due to the Dwarves' strong sense of pride in their race)
 * One sex addicted human Queen (who was well known for having her lovers executed as soon as they started to bore her) was rumored to have taken a horse to her bed
 * While Human/Elf pairings aren't taboo, they are generally treated as a bad idea and very tragic due to the human's mortality and the couple's inability to have children. After a somewhat angsty Human/Elf romance is finally consummated the female Elf gets pregnant. Turns out the father isn't a Human, he's actually a Human/Mage/Demon hybrid, making their child half Elf, quarter Human, one eighth Mage and one eighth Demon. This also gives the father the benefit of immortality due to his non-Human heritage. The child's exteremely diverse genetics are an important plot point in a later novel.
 * Interestingly it is highly suggested that Chakkia, the female Dwarves, are actually a different species than the Chak (male Dwarves). The Chakkia are never described and rarely seen because they are jealously guarded by the Chak. They never leave the Dwarvenholts and are always veiled when out of their personal quarters. Besides intensely different builds and grace, the  of Chakkia seen by Mages is so different that one specifically believes they must be a different species. In another novel a seer recongizes what the Chakkia are, but never specifies it. One book even has a scene from a Chakkia's perspective which included thoughts about what the secret the Chak didn't know about them was. Word of God is that he's not going to explain it.
 * Finally an example that technically isn't Interspecies, but is mostly treated that way in-Universe due to lack of Dracobiology classes: Dragons are exclusively male. They mate (once every 5000 years) with Kraken, meeting at a large whirlpool. After competing for rights, the Dragons throw themselves into the waiting embrace of a Kraken appearing in the whirlpool, going in order from strongest to weakest. The Dragon and Kraken then mate underwater, sometimes resulting in the drowning of the Dragon. The offspring are sea serpents which live several thousand years before a metamorphosis into a Dragon or Kraken depending on gender. Most characters have no clue that the three monsters are the same species.
 * In Tales of the Frog Princess, Li'l, a real, normal bat, meets and falls for Prince Garrid, a vampire. Since she was time travelling at the time, he's from a separate time period. When she finds out about his lies, she goes back to her own time. (It Makes Sense in Context, I swear!) But vampires live forever, so he turns up, saying that he's genuinely fallen in love with her.
 * Olaf Stapledon's Sirius, where it of course turns out badly in the end.
 * A minor yet important aspect of the Sholan Alliance series. Though there it's less "romance" as it is "irresistable urge to have sex between permanently bonded telepathically linked couples". This even allows for the production of hybrid offspring, between both male Sholan/female human couples and between male human/female Sholan couples.
 * ''The Chronicles of Narnia" has several cases. MN mentions the human sons and daughters of King Frank and Queen Helen taking wood nymphs and river nymphs for wives and wood gods and river gods(male nymphs) for husbands repectively. LWW tells that Jadis is descended from unions of Jinn(demons/genies) and giants. PC has Dr. Cornelius telling of some dwafs disguising themselves as humans and taking human spouses and spawing a few half-dwarfs. And VDT and SC tell of Caspian X falling in love with the daughter of the star Ramandu.
 * Dragons in Our Midst has this in spades, as a major plot point is that several dragons were disguised as humans and took on human spouses.
 * Ultimately the case in John Collier's humorous novel His Monkey Wife which is sort of like Jane Eyre if Jane was a sapient chimpanzee.
 * In The War Gods series by David Weber there are 5 races of man, Human, elf, dwarf, hafling and Hradani (filling the role of orcs). All of them can interbreed, but many of the resulting children are sterile. However, each race evolved from baseline humanity in different ways. Hradani and dwarf are more or less true evolutions and are biologic changes to how they tap the magic field. (Both live longer at the cost of reduced fertility and ability to do magic or psonics while dwarves get rock shaping skills and Hdrani become bigger and stronger and are more able to use the magic field to supplement their strength). Haflings are pretty much mutants caused by the last wizard war. Elves though were not part of a subrace as such until the original wizard war ended and secondary casters whose powers are innate and didn't require extensive training to unlock were found to be too dangerous to have their power. They agreed to under go a spell to change how their set of genes tap the magic field so that they lose their magic but gain immortality. As such half-elves are non-sterile, live 400 years, and there is an entire nation run by half elves calling themselves the purple lords. If a half elf breeds with an elf or another half elf, the children are half elves, but if they breed with a human their children are just slightly longer lived than most humans. Elf-dwarf is mentioned as a very sad affair. Half dwarves are non sterile and resulting in alot of mixing with the empire of the axe having dwarves with more than a bit of human blood (resulting in folks having most of the dwarven skills but little shaping abilities) and humans that are a bit shorter than normal due to dwarf blood. Human-Hradani hasn't been seen in ages, but Wencit testifies it's very good they are sterile. Like all half humans they have the potential for wizardry or psonics, at the same time they have the Hradani ability to tap the magic field, resulting in a far higher number of powerful wizards being half Hradani. It's hinted that wild wizardy may be connected to the Hradani ability.
 * The relationship between Captain Laurence and Temeraire is, for all intents and purposes, an Interspecies Romance without the sex. Considering that Temeraire is the focal point of Laurence's life, well...
 * There are distinct shades of this in Dinoverse, in which middle-school children have their minds cast back in time into the bodies of prehistoric reptiles, mostly dinosaurs. The natives are more intelligent than you'd expect, and everyone appears to be the same species, but these are still dinosaurs with kids' minds and actual local dinosaurs.
 * In the first book/two books, a group of Leptoceratops want Canadayce to run away from the Tyrannosaur and join them, Janine quickly becomes close with a native Quetzalcoatlus she calls Loki and half-seriously considers him her 'first boyfriend', and Bertram meets an Ankylosaur who'd just lost her mate and immediately latches on to him, an affection he finds himself returning. These are fairly innocent and for the most part can be interpreted as sudden friendship. Certainly they don't have too much trouble when leaving their new friends to go home. Canadayce "kisses" Bertram, but perhaps because they're incompatible species at the time this does nothing; they kiss more successfully when both are human again.
 * The next books have Patience and an Acrocanthosaurus she names Green Knight. He actively courts her, even presenting her with shiny gifts and nuzzling her at length. When Patience taps into her host body's mind she sees that her host had courted him and pined after him to no avail - he's interested in Patience. Unlike the previous kids, she earnestly falls for him, too, and is devastated when, despondent even when back in her human body and proper time. When it turns out that he's somehow  , they immediately strike the relationship back up. GK's feelings leak over into his human host's mind, so somehow all three are okay with this new situation.
 * In Kurd Laßwitz' early science-fiction novel Auf zwei Planeten (On Two Planets, 1897), German scientist Josef Saltner is taught the Martians' language by the pretty La. They become man and wife.
 * In Thorne Smith's 1931 novel The Night Life of the Gods, inventor Hunter Hawk falls in love with 900-year-old woodsprite Megaera.
 * Uplift:
 * In The Uplift War there is a (partially symbolic) marriage between Robert, son of the (human) governor of Garth and Athaclena, the Tymbrimi ambassador's daughter, though they mostly did it to solidify their species' alliance and both expect to find mates of their own species later. Partly due to the Tymbrimi's extremely humanoid appearance, Robert was seriously attracted to Athaclena for a while, though she deconstructed this trope by pointing out that it wouldn't actually work between them, let alone result in offspring.
 * Male neo-dolphins have a tendency to hit on human women. Sa'ot, for example, in Startide Rising.
 * Interspecies marriage is oddly invoked in Infinity's Shore, when the human Rety rescues a male urs from being eaten by carrying him in her tote bag. Female urs carry their (much tinier) husbands in their pouches, so yee decides Rety is now his wife. She seems fine with that, but it isn't clear whether or not he's actually become attracted to her.
 * 1/2 Prince has a romance between a phoenix and a talking meatbun!
 * Percy Jackson and The Olympians: Being based on Greek Mythology, there's a lot of it.
 * The Game of Rat and Dragon by Cordwainer Smith, who really liked cats.
 * In Taylor Anderson's "Destroyermen" series, it is often hinted and implied that Gunners Mate Dennis Silva and one of the Lemurians, anthropomorphic cat-lemur hybrids, is involved in a relationship. While sexual relations are implied, they are never confirmed.
 * In the fifth book, Walker's Executive officer asks  if he will get in a relationship with a specific Lemurian, referring to it as "going Silva." According to the omniscient narrator, this phrase has ebcome common slang for the humans whenever referring to an inter-species romance with a Lemurian.
 * In the second book a Lemurian.
 * Throughout the series, particularly in the first three books, it is shown that the humans are sexually attracted to the lemurian females due to having similar proportions in the relevant areasand a looser sense of modesty than humans. While this largely occurs because there is a lack of human females, the attraction is still noted.
 * Enchantress From the Stars has Elana, a girl from The Federation, an extremely advanced society, fall in love with Georyn, a young man from a planet stuck in Middle Ages. This is more justified than many examples, as Their species are extremely similar to the point that Elana is mistaken for a native. However, neither of them could be happy in another world, so they part once the Federation's expedition departs.
 * The books by Strugatsky Brothers feature several: Kammerer/Rada Gaal from Prisoners Of Power (Terran human/Saraksh Human), Rumata/Kira from Hard To Be A God (Terran human/Arkanar Human), and Tojvo Glumov/Asya from The Time Wanderers (Homo Ludens/regular Homo sapiens). They all end badly