Humanoid fantasy races, Rubber Forehead Aliens, and the like will have genitalia close enough to the human model that they can get down and dirty with humans or the equivalent. (Most of the time, anyway.) However, there will usually be just enough variance to make the experience... different for the human participant.
If male, the non-human partner will also often be well-endowed. If female, she'll almost invariably lack pubic hair.
No real life examples, please; at least, not until we have evidence that aliens exist.
- XXXenophile: Worked over up, down, sideways, and diagonally in Phil Foglio's comics.
- The Authority: The Alien Applied Phlebotinum that made Jack Hawksmoor the God of Cities have left him with... different genitalia. They are still functional, and he has retained his libido, but the sight of them did cause a doctor to vomit.
- Given far, far too much detail in certain sectors of the Furry Fandom. This probably starts with the relatively tame "Oh my God! Your goolies seem to be on backwards!" (kangaroo or rabbit) to the more unusual aspects of a feline or canine's intimate anatomy. It's best not to ask how these details became common knowledge.
- A common cliche in Kirk/Spock Slash Fic is having Spock's genitalia be green and double -ridged. It's also very common to have them be naturally self-lubricating for obvious reasons. Vulcans also don't have foreskins. Klingons have ridged penises too, just like the ridges on their (spinoff-only) foreheads. This is all on alt.startrek.creative.erotica.
- The Warhammer 40,000 fanfic Love Can BLAM has a Tau woman with an oddly-shaped...yeah, that. It also ignores the canon statement that Tau women do not have boobs. Link is NSFW.
- Also on 1d4chan, the Wet Dream of Selena Agna has an Eldar woman with very few differences from a human woman except for her somewhat elongated figure and her total lack of bodily hair. The human woman in that one doesn't have pubic hair either, though... Link is NSFW.
- Megamind: Being a complete and utter fangirl-magnet (and one half of an extremely popular, not to mention canon, pairing with the film's leading lady), just what Megamind is holding in those tight, leather pants has been explored every whichever bizarre, kinky way that fanfiction writers can think of. (Tentacles seem to be the most popular... )
- The Penguins of Madagascar fic "Princess"; Burt refuses to believe that Julien has a uterus because he's seen Julien go to the bathroom. Julien explains that, being a ring-tailed lemur, he has a pseudopenis (the clitoris is enlarged by high blood testosterone levels).
- In Homestuck, it's never made clear how similar or different trolls are to humans anatomically, as despite having an insect-like lifestyle trolls look like humans with horns and odd coloration. Terms like "bone bulge", "nook", and "seedflap" are used but never explained, meaning that fanfic writers tend to go in pretty much every direction when writing erotica pertaining to trolls.
- Also, buckets are involved somehow.
- In the Romance Reports spinoff Like Fine Wine, it is revealed that dragons have hemipenes like many real-world reptiles.
- Far too many World of Warcraft comics to count make the draenei's face tendrils erogenous zones.
- In the 1988 Alien Nation, human cop Sykes and his newcomer partner Sam Francisco are going through a human murder victim's effects and find a condom.
Francisco: And that fits?
- Wham Bam Thank You Spaceman has aliens whose fiddly bits are their... noses. And yet they still make fun of human genital sizes.
- In The Witches of Eastwick, the Devil-character's penis is described as bending backwards, which is apparently a major turn-on to the witches.
- The comedy film Paul has the title alien remark, "Hey, on my planet, this is small!"
- Star Trek VI: The Undiscovered Country: Kirk is assaulted by a towering alien. Kirk kicks the alien in the knee. The alien promptly drops and curls up in a ball of agony. He is immediately informed, "That was not his knee. Not everyone keeps their genitals in the same place."
- Similar to the above example: "Kay! He's a Ballchinian!"
- Mole-Manic sex is very vaguely described in More Information Than You Require, in that they are said as being eusocial, liking of threesomes, reproducing hermaphroditically like snails, laying eggs like frogs, rearing their young like marsupials, and being fond of blow jobs. Their actual genitalia are not as extensively detailed, except for the fact that they can change gender, and they have something called a "cloacal life sac"...and given what a cloaca is (explained by the "real Life" section down below)...
- Details of the Hunt is about an alien—who has a prehensile dick with Naughty Suction Cup Tentacles at the base—getting involved with a human.
- The Forever War: Subverted in Joe Haldeman's novel; a Mind Probe produced by the Earth military portrays Tauran soldiers raping human women to death with gigantic purple members, an entirely fanciful depiction as at the time the film is made nobody on Earth has the slightest idea what a Tauran looks like, in order to get the human soldiers angry enough to kill. The hero is aware that it is totally false but his subconscious makes his teeth start grinding in readiness to kill! Ultimately they turn out to be an androgynous clone species.
- John Varley
- Gaea Trilogy: The Titanides are basically centaurs with two distinct genders despite looking all female from a distance, but three sets of genitals (only the humanoid-style one of which determines whether they're considered male or female) and a reproductive cycle that makes for somewhat complex familial relationships. They're also reasonably compatible with humans to the point of being able to produce hybrid offspring, which may be somewhat justified in that they're actually a genetically engineered lifeform created by the 'goddess' of their world when it became clear that a first contact with mankind would be eventually inevitable. (Gaea has her issues, but she's shown to be well equipped for creating new lifeforms from scratch.)
- 'The Opiuchi Hotline: Varley is very fond of this trope. The heroine dismisses a potential suitor because he'd had his penis radically modified to fit the latest fetish/fad (he protests that it came with an adapter) and another character who'd gone in for much more radical body modifications is credited for a very creative solution to the question of where a crotchless woman would keep her genitals. In both cases Varley (perhaps wisely) left the actual details to the reader's imagination.
- Steel Beach: Opening line: "The penis will be obsolete within three months."
- In Ursula K. Le Guin's Ekumen series, the Gethenians are physically neuter humanoids who go into "kemmer" (basically heat) and take on the characteristics of one of the sexes. Genly, a human male, spends several years with the Gethenians and is mistaken for a "pervert" or someone who is always in kemmer, which suggests that at least the anatomy is similar, and though they never actually try it out at one point he wonders about whether or not humans and Gethenians are physically capable of having sex with each other. Odds are that they could, since the Gethenians are essentially genetically-engineered humans, created in the distant past as an experiment to see how a lack of gender duality will influence their culture. Almost all human worlds in the Ekumen universe were created as sociological experiments - including Earth.
- L. Sprague de Camp's Viagens Interplanetarias series features a race of humanoid monotremes from the planet Krishna that, while anatomically similar to (but not interfertile with) humans, take considerably less time to climax. For this reason female Krishnans tend to seek out male humans for liaisons, while female humans try to avoid male Krishnans. It's also worth noting that, while humans last longer, male Krishnans were capable of copulating much more often (15-20 times per night).
- Vonda N. McIntyre's "divers" arguably count: The men have internal testes and a retractable penis, mainly for the sake of streamlining.
- Alan Dean Foster's Quozl mate compulsively several times a day, copulate for longer sessions than humans do, and are sexually compatible with us. Hardly unexpected: they're bipedal alien rabbits.
- In the Courts of the Crimson Kings. It's mentioned that the Martian Action Girl and the human Adventurer Archaeologist have physical differences that they need to work around, which only tests their inventiveness. The Martian scientist who examines him later seems rather squicked out by these differences though.
- Orion Arm: The third book of Julian May's series has the main character turned into one of the alien Haluk (on a superficial level). While the twigs and berries are never actually described, there is a reference to there being...well...two.
- Ringworld by Larry Niven: The Ringworld is home to thousands of Pak-descended hominids, nearly all of which are sexually compatible (albeit not fertile) except when their overall body sizes are too extreme and/or one of the prospective partners has to mate underwater. Exotic Equipment does oblige Chmee, a non-hominid alien, to sit out the cross-species games; at one point, he exposes himself to a native to show why he can't participate.
- In Richard Laymon's The Cellar, the Beast is described as having a very ornate member, complete with a retractable tongue.
- The Red Dwarf novel Backwards confirms that the Cat has a barbed penis like his ancestors.
- The Spacers in Samuel R. Delany's short story "Aye, and Gomorrah..." have been artificially neutered in some fashion, although how is only implied.
Live Action TV
KIM: "I've got to be honest, I wasn't expecting something so different."
- Star Trek: Enterprise. When human crewmember Elizabeth Cutler is attracted to Denobulan doctor Phlox, it's not mentioned whether his sixteen-inch tongue is part of the appeal.
- Odyssey 5. In "The Trouble With Harry" hedonist Kurt Mendel shares a couple of his good-time girls with a synthetic human, and is rather disconcerted when they start ignoring him at the first sight of the synthetic's implied larger 'equipment'.
- Babylon 5
- The Narns in are physically and genetically compatible enough (or think they are) to proposition human telepaths in hope of acquiring telepathic genes for their race.
- There are other ways to acquire genetic material from someone, but remember that this is G'kar we're talking about. In one episode no less than three human women were shown leaving his bedroom.
- Another Narn once called him on his attraction to Human females by picking up a pair of panties from the floor of his quarters.
- Centauri, on the other hand, well...Let's just say a Centauri was once accused of cheating at cards using his "tentacles". And as Vir made clearer later, they have six of them.
- Londo was actually shown cheating at cards this way.
- The Tectonese from Alien Nation are anatomically capable of having sex with humans, but mixed couples have to take classes to learn how to get it on safely. Untrained trysts generally result in the human wearing a neck brace.
- The Tectonese can also get their freak on for fun with just the two of them, but if procreation is the desired result they require a member of their specialized "third gender" to act as a catalyst.
- Doctor Who speculates upon this, but doesn't show. "I wonder what else he's got two of?" As Time Lords look indistinguishable from humans on the outside but have Bizarre Alien Biology on the inside, it could really go either way.
- Farscape: Near the end of season 4 in the episode 'We're so Screwed Part 2: Hot to Katratzki' Chiana approaches a Scarran who had ordered her to be cut open in a previous episode and asks him if Scarrans have mivonks. Before he can answer, she knees him between the legs then falls to the ground, clutching her knee. The Scarran looks down at her and says, "Yes. But they're not external."
- According to Neil Gaiman's Don't Panic!, the costumer for the TV version of The Hitchhikers Guide to The Galaxy gave Zaphod's trousers a double fly, suitably padded.
- Implied by the leader of a demon biker gang in the season 6 premiere of Buffy the Vampire Slayer:
Razor (to Willow, Tara, and Anya): Now let me tell you something, children. We're not gonna fight you. We're just gonna hold you down and enjoy ourselves for a few hours. You might even live through it. Except that certain of my boys got some...anatomical incompatibilities that, uh, tend to tear up little girls.
- The Julie Brown song "Earth Girls Are Easy" (inspiration for the film of the same name) has a lot of fun with this trope
"Is that your tongue?"
- And later:
"That sure is a big piece of machinery you've got!"
- Ironically, the film used Male-to-Female Universal Adaptor instead
- Speaking of Joe Haldeman, his Filk Song "The Ballad of Stan Long" has this as its premise, as the narrator is surprised to discover the reason why his titular shipmate/drinking buddy is always a Chick Magnet... and why his admirers always come in pairs.
- In Dungeons & Dragons, elves have no body hair. (It's specifically stated that you have to be a Half-elf to grow a beard, although in Hackmaster, an elf with the Hairy flaw can attain facial hair in the extreme form of an 'Evil Spock goatee'.)
- GURPS: Bio-Tech: "Exotic Genitalia" is a feature available as is "Enhanced Male Primary Sexual Characteristics". But of course.
- The Dark Eye mostly follows the fantasy RPG standard, as evidenced by the existence of half-elves and half-orcs. The reptilian Achaz, however, fall under this trope - they have no visible external genitalia (as evidenced by the picture showing the playable races, where the Achaz is the only one out of eight to not wear a loincloth), and sex for them is purely a matter of procreation, with no fun involved whatsoever.
- Mass Effect: half the Bizarre Alien Biology leads to awkward problems when it comes to sex: risks of infection, chafing, potentially deadly allergic reactions, etc. There are the occasional exceptions, like the asari's infamous ability to mate and produce viable offspring with any DNA-based lifeform ever. Also, according to the veritable database of Interspecies Romance that is Mordin, going down on a drell causes hallucinations.
Mordin: "So don't... ahem, ingest."
- An in-game book from The Elder Scrolls II: Daggerfall, of the Barenziah series (it was censored in later games by an in-game faction) features a mention of the cat-race that is known as Khajiit having barbed penises.
- Implied in Dragon Age. Kossith/Qunari ("Qunari" technically refers to people who follow the Qun "religion", but almost all Qunari are members of the kossith species and vice versa, as such the terms tend to be somewhat interchangeable) are hinted to have genitalia different enough from human beings that a human woman having sex with one of them would wind up severely injured. On the other hand, given the circumstances of the hinting, it's possible that the Qunari in question was just messing with the person he was talking with.
- The conversation could also be taken to imply that kossith simply have very rough sex, like Klingons.
- Gorgeous Princess Creamy Beamy: X Hoshibana has had problems with dating ever since he arrived on Earth. "It's always the same. I meet someone nice, we have a great evening, but then we get back to the bedroom and they just freak out for no reason! What, is something wrong with one of my penises?" The female Usaginarians and Sucrans (confirmed by Word of God to have a common ancestor; "Sucra's made of cake, it'd be hard for meat creatures to evolve on it") also have this problem, with nether ink sacs and vaginas "chock full of spinnerets".
- Implied in Digger with the hyenas.
- The Order of the Stick; the Lizard Folk are apparently structured like real lizards.
"I don't need your standard-issue loincloth, I've been walking around without pants this entire time! It's called a genital sheath, look it up. Hey, while you're at it, look up 'hemipenes', because you can suck BOTH of my-"
Draenei Female: "I'm sure I've got nothing you haven't seen before..."
- In The Legend of Neil, Moblins have three penises, and (unfortunately for Neil) they tend to get aroused by the presence of
- In Zero Punctuation Yahtzee is surprisingly keen to use a prostitute with a feature, or rather three features, only normally seen in marsupials in various simile.
- Stroker and Hoop: In one episode, Stroker attempts to sleep with an alien. He drops his pants, revealing his penis, and she takes off her top, revealing tentacles and teeth instead of breasts. They both scream, "Aah! Put it away!" Later on, it is implied that she is just a human trying to scam him, as Hoop finds a prop of her tentacle breasts, but she is later revealed to be an alien, again, possibly without the weird bits.
- Ugly Americans
- The half-human, half-Devil Callie is compatible with her human boyfriend Mark, including her "threehole", which is less of an orifice and more of a glowing portal she can manifest on her abdomen.
- The show also features a background running gag of a male werewolf / female squid couple. Mark notes that finding a partners whose parts match can be difficult, but by the last episode of the first season, those two (as seen through a peephole) seem to be working pretty well together.
- Manbirds have small, horrifying genitals. They wear boxing gloves over them, and lacking hands, this is what they use to fight.
- The Futurama episode featuring the Lost City of Atlanta has Fry marrying a mermaid. Things get very awkward in the honeymoon suite when the bride asks, "What the heck is that?"
- Non-explicit but apparent example in The Penguins of Madagascar. As with real penguins, the external structure of the eponymous birds is apparently so non-distinct that they literally cannot tell their own sexes without a DNA test, and when Skipper's test comes up female, he believes it.
- In Drawn Together, the princess was cursed with a tentacled netters.
- In South Park, the Gelgamek vagina is three feet wide and filled with razor-sharp teeth.
- My Little Pony Friendship Is Magic: fanon has it, certainly not entirely uninfluenced by the infamous Ask Princess Molestia blog, that unicorn horns are very much like penises, including horn-sucking. It certainly comes in handy given the Fundamentally Female Cast.
- Of course, almost everyone ignores that statement, for various reasons, including biological evidence why it would be unlikely at best for a bipedal mammalian species to lack such assets.