We found him with five partners, each of a different world and sex
The Shore Police were on the way — we had no second chance.
We beamed him up in the nick of time — in the remnants of his pants!
An alien species' sex system is very bizarre in comparison with terrestrial ones. Perhaps it has two sexes that are not identifiable as either "male" or "female" in terrestrial terms, or perhaps it has three or more sexes, each of whom is indispensable for the species' reproduction process.
Of course, Earth has a few bizarre examples of its own. Some species of fungi have more than two sexes (although only two at a time are required for reproduction). There's a species of fish that only has one sex, and among seahorses, the male bears the children. But this only scratches the surface of what writers can imagine.
Supertrope of One-Gender Race. Subtrope of Bizarre Alien Reproduction. May lead to Pronoun Trouble. Compare Bizarre Sexual Dimorphism, Exotic Equipment, and Extra Parent Conception. Contrast No Biological Sex. May be used as part of a Speculative Fiction LGBT story.
- In Phil Foglio's Buck Godot: Zap Gun for Hire's "The Gallimaufry" storyline, a male alien Pog member named Qvakk states that he loved Oort, another male member of his race/species, and was "gonna take him home, make lots of eggs".
- In ODY-C, the backstory includes a Gendercide that wiped out all male humans, and an attempt to fill the gap that resulted in the creation of a new gender, "sebex", who look like Pink Skinned Space Babes and get pregnant by sex with women.
- The silicon-based Jan in Alien in a Small Town have three sexes: the male Workers, who make up the majority of the population; the female Matriarchs, who grow into essentially sessile living mountains and are the leaders of their society, and whose bodies typically contain tunneled passages which are inhabited by other Jan; and the sterile Warriors, who have six arms ending in vicious hooks, huge fanged mouths, and are much much faster and stronger than their Worker counterparts.
- The stsho of the Chanur Novels have three sexes which form mating trios. None of the sexes is quite male or quite female, since a stsho who fulfils the young-bearing role in one mating trio can fulfill a non-young-bearing role in a different trio. Further, if a stsho is subjected to enough psychological stress it might undergo phasing, changing both sex and personality. In addition to the three reproductive sexes, the stsho have five genders: one for each reproductive sex, a fourth for stsho who are undergoing phasing, and a fifth for stsho who are too old to reproduce.
- Bruce Coville:
Gibbons: I am neither male nor female. I'm a farfel.
- Tar Gibbons from the Rod Albright Alien Adventures series insists on gender neutral pronouns because referring to it as male or female is offensive to it. No details are given.
Rod: Is that more like a boy or more like a girl?
Gibbons: Actually, it's more like a pippik than anything.
- The My Teacher Is an Alien series by the same author has Hoo-Lan, whose species needs five different genders just to get an egg, and three more to hatch it.
- The Soft Ones from Isaac Asimov's novel The Gods Themselves are gaseous aliens with three sexes, "rational", "emotional", and "paternal". Being gaseous, they have sex by literally combining their bodies thus merging the three Soft Ones into a single member of what they thought was a different species, the Hard Ones.
- In the short story Hop-Friend by Terry Carr, Martians (or "Marshies") are mentioned to have three sexes.
- Known Space:
- Jotoki are amphibious and look sort of like starfish. They have an immature aquatic stage, and five sexes. Each limb starts as a separate non-sapient creature, which meet and join at maturity, then develop intelligence just before they breed.
- The Puppeteers from the same series claim to have three sexes for PR reasons. The ugly truth is that the "mother" is actually a different species that is parasitized by the Puppeteers in a manner not unlike the larvae of a tarantula hawk.
- Kzin reproduction is close to standard in that they have what we'd recognize as males and females, but the females are non-sentient and basically animals. Male kzinti were enormously confused at meeting other species, such as humans, where both sexes are sapient. It's actually implied that this was not always the case — kzin legends refer to their females having been sapient, once, but they tried to rebel against the Fanged God and lost their souls as punishment. The reality is that after the pre-industrial kzinti destroyed and took the technology of an alien race that landed on their planet, the male kzinti genetically engineered their females to be the way they are now, while at the same time making themselves as strong and vicious as possible to fit with their bronze age ideals of gender roles. A few kzinti populations around Known Space that have been isolated from the homeworld for very long times still have sapient females.
- In Last and First Men, the Eighteenth Men, our many-millions-of-years descendants, have evolved and/or engineered themselves to have as many as ninety-six different sub-sexes.
- Ursula Le Guin's The Left Hand of Darkness takes place on a planet (called "Winter") where people have no permanent sex. They are sexless and asexual most of the time, but from puberty on they turn into a male or a female once a month to reproduce. The same person can be male or female on different occasions, so basically everybody on the planet is both a male and a female and neither.
- There is a story by Stanisław Lem about aliens who, among other things, have five sexes.
- In The Long Way to A Small, Angry Planet, the aeluon have four sexes: male, female, shon (who switch between male and female) and those who are neither.
- In The Culture novel The Player of Games, the Azadians have three sexes - male, female and apex, who are culturally dominant. All three are required for reproduction.
- In Shadow Man by Melissa Scott, humans in the future have seen a dramatic rise in intersex conditions (due to drugs necessary for space travel) leading to five recognized sexes: male, mem, herm, fem, female (clearly influenced by an article by Anne Fausto-Sterling ) and nine sexual orientations.
- The Tralfamadorians from Slaughterhouse-Five have five sexes - and humans have seven. Most of ours exist only in the fourth dimension.
- In a bizarre case overlapping with No Biological Sex, there are apparently seven genders in The Space Trilogy by C. S. Lewis, two of which correspond both to the human sexes and to the genders of the Oyarsu watching over Mercury, Venus, and Mars. The rulers of those three planets have genders, but also have No Biological Sex... it's complicated. When the Oyarsu of Jupiter and Saturn show up, their genders are neither masculine or feminine, which contributes to their already-formidable case of You Cannot Grasp the True Form.
- Star Trek Expanded Universe:
- In the TOS-era novels by Diane Duane, there is one race, the Sulamid that is described as a bundle of bright purple tentacles about six to seven feet high, topped off with a sheaf of pink-stalked and tentacled eyes with triangular pupils and a purplish, "bloodshot" look. According to Dr. McCoy, they have twelve sexes, and all of them claim to be "male," especially the ones that bear the children. The Enterprise has at least three of them among the crew, Mr. Athende in Maintenance, Lt. Meshav from Data Management, and ensign Hwa'vire from Engineering.
- Diane Duane and AC Crispin also have a recurring Horta officer aboard the Enterprise, Dahai Iohor Naraht, who first appeared in Duane's Rihannsu novels and is described as an "orthomale type B-4A". The Horta are a silicon-based species resembling a mobile rock pile, so it's somewhat understandable that their reproductive methods would look nothing like Earth norms.
- The squales in the Star Trek: Titan novel Over a Torrent Sea have four sexes.
- The Jelna Rigelians in the Star Trek: Enterprise Relaunch novel Tower of Babel have four sexes too—endomale, endofemale, exomale, exofemale. Contrast with Zami Rigelians, who have the usual two sexes, and Rigelian Chelons, who are hermaphrodites but accept gender identities due to centuries of cultural imposition by the Jelna and Zami.
- The Andorians have four sexes in the Star Trek Novel Verse as well, based on a line in the Star Trek: The Next Generation episode "Data's Day" that Andorian marriage involves four individuals.
- The listeners from The Stormlight Archive have four sexes, with almost any given individual belonging to two of them over the course of its life. The listeners have the standard two genders (masculine and feminine), but these are each further subdivided into fertile males and females and infertile malen and femalen. To make matters more confusing, the listeners are limited shapeshifters, able to assume any one of several forms to fill various social roles. One of these is the fertile and sex-obsessed mateform.
- Tales of the Jokka: The Jokka created by M.C.A. Hogarth have three genders, anadi (female), emodo (male), and eperu (neuter). They can also change genders up to twice in their lives, the causes aren't entirely clear.
- In The True Meaning of Smekday by Adam Rex, the Boov aliens who attempt to enslave the human race have 7 sexes that translate in English to: girl, boy, boygirl, girlboy, boyboygirl, and boyboyboyboy.
- "Venus and the Seven Sexes", a 1949 short-story by William Tenn, features a seven sexed species that passes gametes in a chain: sex "D" receives from sex "C" and transmits to sex "E." The sex of the offspring is determined by the sex of the parent which receives/completes the fully fertilized gamete. One sex is tasked with coordinating the family.
- Bob Shaw's Warren Peace duology has the Squelchers, an alien race with no less then six different sexes, each one with its own unique appearance, and with a reproductive cycle where each sex fertilizes the others in turn. The forms look so different that, to the vast majority of the universe, the species only consists of the fourth sex, which resembles an orange-haired, saggynote sasquatch with multiple eyes in a ring around its head (usually covered by its fur), oversized feet that let it wade on water, and two giant red nipple-like gamete sacs positioned one above the other on its torso. The fifth sex, the only other one mentioned, is described as being indistinguishable from a tree, except for the presence of a pair of two dual-pronged ovipositors sprouting from its trunk. Their introduction revolves around a plot in which Squelcher workers are wreaking havoc on the delicate, water-based flowers they need to harvest by constantly having orgasms from what their human superiors presume are super-explicit pornography. It turns out that the problem is the staples in the various magazines provided for recreation; they look just like the ovipositors sported by the fifth sex.
- Star Trek:
- In Star Trek: Voyager the hostile "Species 8472" is reported to have as many as has five distinct sexes, at least according to Voyager's medical hologram but he admits they don't know anything else about their reproduction.
- Star Trek: Enterprise:
- One episode features a race called the Vissians, who as well as having males and females have a third gender called "cogenitors" who are necessary in reproduction but only account for 3% of the population of Vissians. Cogenitors are third class citizens not even given names or an education, they are circulated between couples to assist in reproduction.
- Andorians, as revealed in the expanded universe, have four separate genders, all of which are needed for reproduction.
- The Goa'uld in Stargate SG-1 are a two-sex race that doesn't match up with Earth norms. The majority of Goa'uld appear to be biologically male but tend take the gender identity of their host, with a very small minority being biologically female "queens" that produce larvae. While queens can reproduce asexually, fertilization by a male passes his genetic memory to the offspring; for this reason, what few queens exist are kept as trophy wives by powerful system lords.
- In Myriad Song Elvers have four sexes, male, female, midwife and neuter. Elvers are all born neuter and change to one of the breeding sexes at twenty based on the gender composition of the surrounding community, individuals isolated from others of their species may be neuter for life. Midwife carries fertilized eggs in a pouch and provides hormones.
- Warhammer 40,000: Tyranids don't have defined genders and, due to the way all of their weapons work, would technically qualify as either female or hermaphrodites (their weapons produce and gestates eggs, then launch the resulting creature at the enemy in the most horrifying way possible). Anything larger than a bullet would be created via the Norn Queens aboard the Hive Fleets, to which no one knows how the process is suppose to go. Genestealers are even weirder, as they can impregnate host species with their own genetic material, but the host itself still needs to reproduce naturally to pass on said genes effectively giving the child three parents.
- In Rocket Age the Europans have 5 genders in total, male (25%), female (25%), neuter (25%) and two unclassified genders (25%). Because the Europans are incredibly secretive, no-one is exactly certain how their reproduction even works and even the classifications Earthlings have given the known genders could turn out to be wildly wrong.
- Numenera: The skeane — an alien species vaguely resembling emperor penguins with fluke-like, bony tails and six limbs, four ending in seal-like flippers and the front two in webbed hands — have three sexes: egg givers, who produce a small egg once a year; egg takers, who take it into their bodies and brood it until it's ready to hatch; and feeders, who feed the young by regurgitating a special nutrient fluid. These sexes are physically identical to each other in almost all respects, with the only occupation being the presence or absence of white nodules underneath their tails: givers have two, takers four and feeders none.
- The insectoid Shirren in Starfinder have male and female members in addition to a third sex called "hosts"; males and females contribute eggs and sperm for reproduction, while the host carries the eggs until the offspring are born in addition to contributing some of their own genes into the trio's young.
- The Real-Time Strategy Achron has the Grekim, a race of Time Travelling alien cyborg squid with three sexes (octo, pharo, and sepi) and three "classes" (basic, pod, and ligo). Any two members of different sexes may "progenerate" a member of the third sex of the same class or the next one up (e.g. a pharo and a sepi can produce an octo or an octopod, or an octopod and a pharopod can produce a sepipod or a sepiligo). This is the species' primary method of producing units; although the exact details are unclear, a certain amount of proximity is needed but it does not require physical contact. Ligo cannot "progenerate", but can "split down" into two basic units of the remaining genders (e.g. an octoligo can split down into a pharo and a sepi).
- Cthulhu Saves the World has party member Paws, a cat-like alien, explain that his species technically has every member as a unique gender. However, for sake of convenience, he allows the party to refer to him as "he".
- The X-Universe:
- Boron have a third sex, called "Lar", in addition to males and females. The presence of a lar is not strictly necessary for reproduction, but it is described as being "beneficial". Lar prefer to be referred to with female pronouns and it is noted they make up the majority of the Boron leadership.
- The Paranid have 11 sexes. Extra Parent Conception is implied to be required judging by the species fetish for the number three, and the precise parental combination will affect the development of the larva.
- Subnautica: The PDA mentions that every species on the planet 4546B has a single sex which can both fertilize and carry eggs as most of the creatures still need mates to reproduce, however the PDA also states that some of the species are capable of asexual reproduction in case the population gets to low.
- Civilized space in Orion's Arm recognizes six Transhuman genders, approximately defined as male, female, hermaphrodite, female pseudohermaphrodite, male pseudohermaphrodite, and genderless. Things pretty much go out the window when you bring actual aliens into the picture.
- The speculative alien species Triaformica has three sexes, due to being descended from fungal ancestors. Likewise, only two sexes are needed to reproduce at any one time.
- Most aliens in the Humans are Space Orcs blog are referred to with nonbinary pronouns. No word on wether these are biological sexes or psychological genders, however.
- According to his Character Blog, Gravity Falls' Bill Cipher's home dimension has 14 billion different genders. He claims that he has not decided on his own orientation simply because of how much paperwork it would entail.
- Home: Adventures with Tip & Oh In one episode, Oh explains that Boov have 7 genders: boy, girl, boygirl, girlboy, boyboy, boyboygirl and boyboyboyboy.
- Tetrahymena thermophila, a single-celled protozoan, has seven different sexes (or rather, 'mating types', distinguished by a single chromosome) and can mate with any other sex except its own. That way, it increases the chance of finding a suitable partner, as well as provide a wider pallette to mix and match genes and add genetic variety to its offspring.
- Some species of worms have three sexes: males, females, and hermaphrodites. While hermaphrodites are able to ferilize themselves, this produces genetically-identical offspring, so the worms switch between asexual and sexual reproduction to ensure genetic diversity, as well as found new populations without the need for a mate.
- The nematode Caenorhabditis elegans consists of males and hermaphrodites instead of males and females. In the event that a hermaphrodite cannot find a male to mate with, it can self-fertilize.
- The Iberian minnow (Squalius alburnoides) consists of two distinct but linked lineages, one consisting only of diploid males and the other consisting of triploid males and females. The diploid males mate with triploid females to produce only diploid male offspring.
- Fungi have over 36,000 sexes, (technically called mating types - think sex-lite) but only two are needed at any one time to reproduce.
- The white-throated sparrow (Zonotrichia albicollis) is moving towards four sexes. Males and females are either white-striped or tan-striped. White-striped males are big philanderers that don't care for their young, butt into others' territory and have high testosterone. White-striped females are aggressive nymphomaniacs who palm off the child-rearing responsibility onto their mates. They're monogamous, though. They always mate with tan-striped birds and the tan-striped birds are more devoted parents, less aggressive and not as horny. And it looks like the chromosome responsible for these differences is turning into a sex chromosome.
- The Cape honeybee (Apis mellifera capensis) reproduces by parasitically cuckolding the better known "killer bee." The Cape honeybees have a unique caste known as a pseudoqueen, which don't work like workers but don't reproduce as often as dedicated queens, which use mind control pheromones to trick the killer bees into killing their own queen and caring for the Cape honeybees. When the host colony eventually dies, the pseudoqueens fly off to find new host colonies and repeat the process.
- Any given hive of eusocial insects will have three sexes within the Hive Caste System: male drones, sterile female workers, and a fertile Insect Queen. Some species, especially among ants, go even further by specialising the workers into sub-castes like soldier ants.
- A male anglerfish only exists to fuse himself to a female's body and degenerate into a pair of testicles. This can occur an indefinite number of times, so a female anglerfish can gain an indefinite number of ballsacks.