Whenever a character has no genitals or secondary sex characteristics. They may identify as masculine or feminine, or they may have an entirely different gender identity. This is frequently a trait of spirits and spiritual beings, who don't have physical bodies in the first place. Note that due to a lack of alternate phrases in the English language, referring to a character as "sexless" does not mean that they're Asexual, which instead deals with sexual orientation and attraction, nor does it mean that a character does not or cannot have sexnote No, we're not renaming this trope again. If Everybody Wants the Hermaphrodite is in effect they may in fact have a very active sex life.
Finally, Intersex people have sexual characteristics, but they may be ambiguous or mixed, not fitting into either sex category. Characters like this sometimes run into Pronoun Trouble if they don't identify with a specific gender, even though options such as "zhe" and "hir" do exist, and the singular "they" is grammatically acceptable.
Sometimes a trait of a One-Gender Race. Not to be mistaken for G-Rated Sex, but can overlap. Often overlaps with Otherworldly And Sexually Ambiguous when a character is explicitly supernatural and this trait is used to emphasize it. Compare Ambiguous Gender, when the character does have a physical sex but the viewers/readers simply don't know what it is, and Barbie Doll Anatomy, when the body parts in question are presumably meant to be there but are not drawn for censorship reasons. Also compare Purely Aesthetic Gender when the gender of a video game character is completely irrelevant so that they might as well have No Biological Sex as far as the plot is concerned.
Ashura in RG Veda is explicitly said to have no physical sex as part of a curse to end the line of the Ashura clan with them. In addition to this, they are also genderless.
In X1999, Nataku is similarly sexless as a result of cloning. In the manga, it's implied that their gender is female, likely due to the fact that their genetic source was a young girl named Kazuki.
In Wish, all angels are explicitly genderless, although many international translations incorrectly used gendered pronouns.
Ruby Moon from Cardcaptor Sakura is genderless, but chooses to present herself as female because, as she puts it, girls get to wear cuter clothes and uniforms.
Hana from Gate 7 is strongly implied to be genderless - Sakura calls into question whether or not Hana is female, and then, in response to Chikahito's confusion, neither confirms Hana's masculinity nor offers any form of clarification.
A Shrug of God has also hinted that the Zashiki Warashi from ×××HOLiC may not necessarily be either male or female, playing off old portrayals of the spirits in mythology and artwork, where their gender was often unclear.
In Fullmetal Alchemist, the true form of Envy is a large lizard-like thing with the head and shoulders of the people of Xerxes sticking out. It doesn't seem to have genitals of any sort. Picture here,◊ if you're brave enough to see, and their TRUE true form is what can best be described as a fetus.
Wagaya No Oinari Sama's Kuugen is a Kitsune and too old to remember their original sex, if they ever had one, and just switches between male and female forms on a whim. Justified in that Kitsune are spirits in the first place, and tied to the kami Inari (see below).
The Shinigami of Death Note do identify themselves as male or female (meaning that they do in fact have genders), but it is clearly stated that they cannot have sexual relations of any kind, and odds are that they don't have any sexual organs, and even if they do they're most likely non-functional.
Puella Magi Madoka Magica has Kyubey. Fans generally refer to it as male since it uses Japanese speech patterns and pronouns that suggest a male identity, but it really doesn't seem to be either one, being a Starfish Alien whose true form is hinted to be something entirely different than what we see on screen.
Digimon of Digimon Tamers are technically sexless, being mere data, but their manifestations often take the form of specific creatures with genders for purely aesthetic reasons, something Renamon explains to Ruki. Either way, they do not reproduce sexually. Apparently not the case in Digimon Xros Wars, which doesn't hold back with the implications of sexual relationships between Digimon. One of the supporting mons in Taiki's team even has parents who appear on-screen, and the Big Bad Duumvirateare brothers. Ironically, Lilithmon is made fun of at one point for not having a boyfriend.
UQ Holder has Kuromaru, a member of the yatagarasu tribe of demihumans, who have no gender or physical sex until the age of sixteen.
All angels in the expanded Vertigo universe, which means they've made several appearances in Hellblazer, The Sandman and their respective spin-offs.
The Preservers of ElfQuest explicitly have no physical sex.
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 of his species/race, and was "gonna take him home, make lots of eggs"; Pogs appear to be reptilian-like evolved turtles(with the subsequent cloacal implications included), and no other or female members of their species are shown, which implies this trope.
The Venom Symbiote from Spider-Man counts as this. Venom is a sapient mass of black, blob-like alien matter, which envelops the flesh of its host and bonds with them on the genetic level. This bonding manifests as black coating on the outward exterior of its host, so in this sense the shape Venom takes can either be masculine or feminine depending on its host (there have been She-Venoms for when it took females as a host, so its not just exclusive to males like Spider-Man or Brock). In its natural state Venom has no sexual characteristics and identifies with no gender, and the default pronoun people use to describe Venom is "it". Though in Peter Parker's case he has been known to mock Venom as acting like a "jealous girlfriend" when it comes to wanting to fuse with him again and kill anyone who stands in its way of assimilating with Spiderman again, but that's just him being snarky rather than any serious gender identification. In addition Venom is capable of asexual reproduction, as it has independently produced other symbiotes such as Carnage.
The IDW run of Transformers started out with the concept that all Transformers were genderless. Male pronouns were used, but that was often justified as Translation Convention. Arcee's origin story introduced her as a genderless bot experimented on and made into a female (who went a little insane over the whole thing). This naturally had all sorts of Unfortunate Implications.
Later comics would introduce "naturally" female Transformers who developed on another planet. If this means there are "proper" male Transformers out there too is not yet known. In general, the writers are eager to move past this issue and its Broken Base and are now effectively treating the non-gendered Transformers as male retroactively.
Metatron, the Voice of God, in Dogma. And all the other angels, though it's implied that they did have physical sexes at one point before God gave them the physiques of Ken dolls as punishment. And Serendipity (a muse) does not have one either.
Satan in The Passion of the Christ is portrayed by a woman with a shaved head and a voice altered to sound more masculine in post-production. This fits in with Thomas Aquinas' writings, which specifically refer to angels, of which Satan is a (fallen) one as being pure spirits, and therefore not possessing a physical sex (see below).
In Seed Of Chucky, Glen(da) was born a living doll with Barbie Doll Anatomy, and isn't sure which gender to favor, if any. Chucky and Tiffany spend most of the movie arguing over their kid's gender.
Folklore, Religion and Mythology
Many angels in religion and mythology.
The Bible: YHWH technically doesn't have or need a physical sex. Being an unfathomable entity, this is a given. In the past, God has been arbitrarily assigned male gender nouns and pronouns because 'It' is disrespectful and His people were originally patriarchal (plus there is the little fact that Hebrew has no neutral gender). However, feminine nouns are sometimes used in Jewish religious literature when God is credited with female gender characteristics such as nurturing and tenderness. The ancient Hebrews even used plural words for God sometimes, while Christians are much more likely than Jews or Muslims to think of God as male because He got a woman pregnant and sired a male who was also Himself, in a way, depending on which Christian sect you ask.
The Prince of Egypt references the Jewish tradition of female pronouns being used to refer to God in some instances by having God as the burning bush speak with a primarily male voice (provided by Val Kilmer—the same person who voices the character God is talking to) with a whispery female voice layered into it. They had also originally planned to have a third voice, that of a child, added into the mix to further the ambiguity (the combination turned out to be way too demonic-sounding, so it was dropped).
The Christian interpretation technically averts this, since Jesus (who is part of the Trinity) is a man, regardless to what applies to the other parts of the trinity. It occasionally given as one of the reasonsnote The other reasons, being exceedingly technical and concerned with theological and historical minutia, need not be discussed here. why Catholics will only allow men to serve as priests.
Angels are also sometimes thought to be genderless beings as well, at least according to some interpretations of Jesus's statement: "At the resurrection people will neither marry nor be given in marriage; they will be like the angels in heaven." (Matthew 22:30).
Inari Okami, the Shinto God of fertility, rice, agriculture, foxes, industry and worldly success, is generally considered to be neither male nor female, though like YHWH, masculine or feminine aspects are often emphasized depending on the context and the region. This is true for many other Kami as well.
Diaspora features a society of posthuman software people who rarely choose to be gendered, along with invented gender-neutral pronouns (ve, vis and ver) first used in Distress, where meat-humans sometimes elect to become 'asex'. (Some others crank their secondary sexual characteristics Up to Eleven, and become 'umale' and 'ufem'; still others make a sort of blue-and-orange gender binary called 'imale' and 'ifem', which uses nonstandard gender cues.)
Schild's Ladder features essentially genderless posthumans but retains both male and female pronouns.
Carolyn Ives Gilman's Halfway Human: On Gammadis, the modified-human inhabitants have no sex until puberty. Some people never go through puberty and remain unsexed all their lives, being known as "blands." They are considered to be not fully human, are widely believed to be mentally deficient, live segregated, and work as servants.
Comes part and parcel along with Easy Sex Change in John Varley's Eight Worlds science fiction series. Some people will always pick "none of the above" if given the chance to choose. For some it's permanent, for others it's temporary. One character describes it as a "vacation from sexuality."
Golems on Terry Pratchett's Discworld. Most are referred to with male pronouns, for the usual reasons. In Going Postal one was arbitrarily declared female (and named Gladys) because Ms Macclariat took exception to anything called "he" cleaning the lady's bathrooms. When questioned about this in Making Money, Moist points out that the 'default' golems aren't any more male than Gladys is female.
Very scary example from Dean Koontz' The Bad Place: the villain (child of a hermaphrodite with him/herself) has four undescended testicles (with a bony shelf in the way) and no external genitalia. He channels his necessarily-repressed sexuality into homicidal rages.
The Ainur of J. R. R. Tolkien's works. As pure spirits, they have no biological sex beyond that of whatever form they've taken at the time, but explicitly do have gender identities (or at least, identify themselves in a way comparable to mortal gender). They are also capable of sexual reproduction with non-Ainur species in the standard biological manner appropriate to their body type.
Similarly, in C. S. Lewis's Space Trilogy, the Oyarsa (basically guardian angels, Earth's being Lucifer) of Mars and Venus can be described as masculine and feminine, respectively, but only because these genders arose from intelligent life imitating them. The other Oyarsas do not conform to either, but each have their own genders.
The Gethenians from The Left Hand of Darkness have no sex for most of the time, except for a few days each month when they go into kemmer and become male or female, returning to androgyny afterwards. The sex during kemmer can change from month to month—a father of one child could be the mother of another.
Xantcha from the Magic: The Gathering novel Planeswalker. The Phyrexian Newts were created to resemble humans, but the first generation was defective in certain aspects, including lacking a physical sex. Mentally, Xantcha began thinking of herself as female after she was Mind Raped by the male demon Gix.
Yime Nsokyi from the Culture novel Surface Detail has deliberately had herself neutered. However as everyone seems to identify her as female and the narration always does the same it seems the purpose was more to eliminate sexuality than anything else.
Chieri, the dominant native race of Darkover are hermaphroditic but some of their hybrid offspring with humans are 'emmasca' or neuter.
In the Book of Night with Moon series, spayed and neutered cats are considered to be the same gender, and not the same as toms or queens. However, they're still referred to with male or female pronouns and most other gender markers, although this could be the Translation Convention at work.
In Time Scout, Armstrong is a character with an ambiguous sexual identity. He could be a feminine man. She could be a masculine woman. She never identifies as either and he can pass for either. His hair is cut short, she wears wigs, and long-necked clothing eliminates the possibility of seeing an adam's apple.
The Mrdini of Anne McCaffreyTalents series lack sexes altogether, and prefer to be referred to by the pronoun "it". While they do require two individuals to reproduce, any two individuals will do.
Kyree, an intelligent wolf-like species in the Heralds of ValdemarVerse, can be male, female, or neuter. Since the neuters lack reproductive responsibilities to the pack they tend to be the ones that go out and have adventures, and are therefore most often encountered by others. The most prominent kyree character, Warrl, is referred to as male, with occasional notes that this isn't technically accurate.
MYCROFT from The Moon Is a Harsh Mistress has no sex as he's, you know, a computer. He developed his male personality under the guidance of Mannie, the protagonist. It took a woman to realize that a computer isn't in any way more male than female (Mannie was somewhat surprised by that), which led to Mike developing the alternate personality of MYCHELLE.
In Bone Dance, Sparrow is revealed to be this, due to having been created as an all-purpose vessel for a group of Body Snatchers.
The alternate timeline Morlocks in Stephen Baxter's Time Machine sequel The Time Ships have no sex and reproduce artificially. The main Morlock character is still referred to as "he", though.
Implied in Animorphs: when the future Visser One first sees humans she describes them as "gender differentiated, like Andalites and Hork-Bajir"—thus implying that Yeerks (and Taxxons?) aren't. Yeerks are generally referred to by their host's gender, though, or the gender that the narrator thinks of them as.
The Dark One of The Wheel of Time is usually referred to as male (probably in part because Ishamael, who is a man, presented himself as the Dark One for millennia). However, when Rand finally confronts it directly in the last book, he sees it in its true form as a sentient void, and realizes that the Dark One has no gender. The remainder of their confrontation mostly uses "it" as the pronoun of choice.
The ur-viles (and their Defector from Decadence offshoots, the waynhim) from the Chronicles of Thomas Covenant have neither biological sex nor gender identity, and are always referred to as "it". Justified, because they are artificial beings created by the demondim, who were in turn created by the Vilesnote Each group, motivated by self-loathing, was trying to create beings radically different from themselves, leading to the transition from pure spirits to undead creatures to physical living beings; ur-viles can't reproduce by natural means, instead apparently growing new ur-viles in vats.
Angels in Good Omens are specifically stated as being sexless and asexual (fanon usually ignores this completely). It can be inferred they take on masculine/feminine appearances to cut down on confusion with the mortals, or just out of habit.
Asgard from Stargate SG-1 are biologically sexless due to the cumulative effect of generations of genetic drift and alterations since they switched over entirely to cloning as their sole means of reproduction. They do exhibit personal gender though, as they are also all uploads of individuals who were born naturally, many thousands of years ago. Eventually, we are shown what they originally looked like (essentially pearlescent grey humans) and the contrast with their current existence as classic Roswell Greys is quite severe.
The character Q from Star Trek: The Next Generation counts. As the Q Continuum are composed of bodiless Energy Beings, who have neither flesh and blood bodies or inherent genders, the physical form(s) they appear in are nothing more than an avatar they use to allow them to interact with mortals (mortals can't exactly talk to or touch giant balls of energy). The most prominent Q in the Star Trek series, who debuted in Next Generation, assumes a male form (portrayed by John De Lancie) in his interactions with Captain Picard, but does point out to Picard that he could assume a female form if he had chosen to; making a point that gender for a Q is a transitory, and ultimately arbitrary concept. Despite pointing this out Q never assumes a female form around Picard in the TV show's canon (though in the Expanded Universe Q assumes a female form and boasts to a group of Starfleet officers how s/he "seduced" Picard in that form, though the validity of this claim is never verified by Picard himself) Additionally Q reproduction and sex does exist, but as energy beings it is independent of the physical bonding as we mortals know it; Q sex is based on drawing out energy signatures from partnering Qs to provide pleasure, but if the 2 Qs in question combine their energy signatures they can create a new Q with traits from both. Though it has been proven that thanks to their shape shifting powers that Qs can take advantage of mortal reproductive abilities, showcased in the example of a woman named Amanda Rogers who grew up thinking she was human because her parents assumed human form and gave birth to her the old fashioned way; however, since they died shortly after she was born Amanda didn't learn she was a Q until recently.
The Daleks in Doctor Who. They all speak with electronically-generated voices that sound masculine and use the male title "Emperor" for their leader, but are actually genderless and seem to be only able to reproduce through cloning or genetic corruption of other species (particularly humans). They are always referred to with 'it' pronouns in Expanded Universe media. We only encounter males of their precursor race, the Kaleds, leading to some to speculate that they were a One-Gender Race, but the Doctor's statements about how close the Kaleds and humans are to one another biologically and the fact that the only Kaleds we've seen so far were in a Nazi-like military setting suggests female Kaleds did exist, but if any were converted into Daleks their gender was erased. The only definitely female-identifying Dalek seen so far was in "Asylum of the Daleks", and her identity as a woman was explicitly shown to be a symptom of her madness, as biologically she was a Dalek like any other.
Warforged from the Dungeons & DragonsEberron campaign setting are sexless. They may have a gender identity, but given that they have no biological basis for it, they generally either go along with whatever those around them label them, or just pick whichever feels right. While Changelings have a "natural" sex, they are able to take a sexless form, and it is pointless outside of high level magic and the Unsettling Gender-Reveal that leads to Fantastic Racism.
Angels and demons in In Nomine are technically neuter, although many that spend time on Earth end up acquiring a gender-bias, depending on which sex of vessel they most often have. Elohim don't acquire such biases (they are by nature supposed to avoid bias) and Kyriotates and Shedim switch bodies so often they usually don't imprint on any one gender, and Lilim generally identify as female.
Orks in Warhammer 40,000 are sentient fungus/algae hybrids that reproduce independently through spores note in real life many fungi actually have a system of Bizarre Alien Sexes rather than reproducing asexually, but then, the Orks were bio-engineered as Super Soldiers by Sufficiently Advanced Aliens and asexual reproduction does allow them to take over planets a lot faster. They act extremely male, however.
Necrons, being robot skeletons, are similar. The sentient ones are generally referred to with male pronouns, if only because they look and (especially) sound masculine by human standards. It's unknown what, if any, genders or reproductive methods the organic aliens they were created from originally had.
Gods in Exalted have whatever gender (if any) that most suits their nature, and can generally carry children or impregnate others regardless (although some may temporarily change their sexual characteristics to accommodate it). Demons are apparently more strictly codified.
Xantcha from Magic: The Gathering has no sexual organs, physically mostly resembles a thirteen year old boy (despite being over 3000 years old) and identifies as female.
Most BIONICLE characters are meant to be biomechanical, that is, cyborgs, but it wasn't until the 2009 setline that the concept of biological gender was officially introduced (disregarding the occasional organic creatures like sea squids that we have seen before). The gender of Matoran Universe beings is defined solely by their personalities, whereas non-MU characters are organic by nature and their robotic parts are only implants. Thus, there is No Hugging, No Kissing in the MU either.
Most Pokémon in Generation II and beyond have sexes, but some do not. Some of the sexless Pokémon can breed with a shapeshifting Ditto, and some legendary Pokémon with genders cannot breed (Latios, Latias, Cresselia, Heatran). Certain legendaries, such as Mewtwo, Rayquaza, the Kanto birds, and the Sinnoh and Unova dragon trios have neither sex nor breeding capacity. This last group fits this trope.
Manaphy is sexless, yet it is capable of producing offspring - Phione, who is also sexless and unable to evolve into Manaphy.
Some fans have said this about NiGHTS. Others say that it's a case of Ambiguous Gender. It doesn't help that Sonic Team never really gave a straight answer. In NiGHTS: Journey of Dreams, NiGHTS was given a voice actress whom sounded both like a young boy and a slightly older girl at the same time. But it's basically up to the dreamer and the player as to what gender, if any, NiGHTS is.
In Choice of Dragon when given the choice of gender, you can choose neither, unknown, or simply refuse to answer.
Furcadia allows you to make characters who are 'neuter', in addition to the standard males and females, who have their own portraits. All three sex options use the same sprites.
Cloud of Darkness, as seen in Final Fantasy III and Dissidia: Final Fantasy, appears female (particularly in the latter) and is referred to with female pronouns... but as the name implies, she's just the physical form of a literal cloud of darkness, and actually refers to herself with "We", apparently including sentient tentacles in that. Therefore, she can't be said to be female.
The two requisite wise mystic thingies in the Ecco the Dolphin series, the Asterite and the Guardian, are a sexless giant strand of DNA and genderless giant psychic crystal, respectively.
In the Konami series Parodius, the scoreboard asks your gender. They're prepared for boys, girls, everything in between AND everything neither here nor there.
Similarly, the early Ultima games had sex and gender on a slider, so you could be male, female, or anywhere between the two.
Fi of Skyward Sword, according to Word of God, is a feminine figure, but doesn't really have a sex per se. Fitting, since she's a sword. Given that Ghirahim is also revealed to be a Living Weapon akin to Fi as well, the same can most definitely be applied to "him."
Many of the viral monsters in Prototype are sexless - Hunters are built to fight, not reproduce, for instance, and that extends to the Supreme Hunter despite it being humanoid (sometimes extremely humanoid). This also extends to the player character, Alex Mercer, who seems to identify as male, but is technically just a person-shaped virus and a shapeshifter with no truly fixed form or means of sexual reproduction. The Blackwatch persistently refer to him as "it".
In The Elder Scrolls series, the Daedric Princes are pure spirits who sometimes manifest on the mortal plane, but do not have a physical sex and several of them seem rather cavalier about changing genders. As a result there are several who are referred to as male at certain times and female at others — sometimes in the same sentence.
Orochi of The King of Fighters, while commonly referred to as a "he", technically is sexless, as it's implied that the entity's appearance is determined by whichever follower of his Orochi decides to reincarnate into and that his true form is the eight-headed serpent dragon of Japanese myth. His incarnation at the end of KOF '97, where he resurrects using Chris, is his most well-known depiction, but The King of Fighters: Kyo and official artwork viewable in '98 clearly portray Orochi as a woman during the fated battle that ended with Orochi's sealing.
The Super Mutants in Fallout 3 appear and sound masculine, but were all rendered sexless by the FEV mutation process. Some of them were indeed female when they were human. This only applies to the Capital Wasteland Super Mutants, every other known example still has the primary genitalia but the females do lack breasts.
Luna of Ratchet & Clank: Size Matters. She's built to resemble a little girl, but is actually a genderless warship/puppet built by the Big Bad to kidnap Ratchet. It helps that Luna gets a male voice shortly before it's defeat.
Fairies in Eternal Eden are said to have no gender, although they appear feminine and the narrative generally treats them as females.
Shale and presumably ally other golems from Dragon Age: Origins due to their bodies being entirely artificial. Their souls, on the other hand, are implied to keep some concept of gender in some cases, and Shale is quite surprised to find out that she was originally a dwarven woman.
Bramimond from Fire Emblem lost his/her/its entire identity, including gender, as a result of practicing dark magic, so Athos refers to Bramimond as "it" rather than "he" or "she."
This is also implied to be the case for Tavrisprite, a fusion of Tavros and Vriska, doubly so due to being a sprite and being a combination of two characters of the opposite gender.
Caliborn and Calliope, two alien characters called Cherubs who share a body. While they identify as opposite genders their body is physically ambiguous, and it's later revealed that their entire species is like this, with the female and male halves battling for control over the body until one eventually wins, at which point the body takes on more secondary sex characteristics, but both genders are capable of getting pregnant. For bonus points they are named after the main character of Middlesex, who was intersex.
The trolls have genders and secondary sexual characteristics (specifically: females have Non-Mammal Mammaries, or at least something that appears to be that, while males don't) but how these relate to reproduction is, at best, ambiguous. It doesn't seem to matter whether Matesprits or Kismesises (the two "reproductive" troll relationships) are of opposite genders or not (one troll reacts to a human saying he's not a homosexual by first being confused and when it's explained asking "HOW IS THAT EVEN A THING?"). Trolls don't physically mate in person, and the process apparently involves pails of "mating fluid" from several individuals being mixed together, so possibly there is actually is a biological difference between the genders and the concupiscent relationships just make the goo "better" somehow. Many fanfics portray trolls as effectively being Hermaphrodites.
Landorus of Black Adventures says, "I am no more female than I am male. And I don't have any -parts-, so... it's ironic that I was once worshipped as the 'Kami of Fertility.'" after Professor Juniper asks if Landorus is female due to their feminine appearance.
Carbosillicate amorphs like the titular Sergeant Schlock of Schlock Mercenary reproduce by methods having nothing to do with the traditional concept of sex as practiced by humans. Reproduction can be accomplished by a form of asexual budding with the resulting new amorph's personality being based of the parent and a partner (who doesn't even have to be of the same species) that is imprinted at the budding stage. Alternatively they can reproduce my mixing together parts of two separate amorphs in a form of pseudo-sexual reproduction. Those who hang around humanoids tend to identify with a gender but still don't attach any gender issues to reproduction.
In Shortpacked!, Ultra-Car starts off as a sentient car, then gets put in a female-looking robot body. When other characters are surprised by the implication that Samus Is a Girl, "she" sarcastically replies that "she" never had a gender; everyone else just decided a sexless car was male. She now calls herself a "trans-chassis woman".
Other than the use of the male pronoun for convenience, there's no gender baggage that GIR has to deal with. He already has enough problems to deal with.
This also appears to be the case with Irkens, because they are so far past The Singularity that they are reproduced only by machines, though they do have genders.
Transformers are robots and as such have no sexes to speak of, although male seems to be the default where pronouns are concerned.
WALL•E and EVE are canonically without sexes, as are the other robots. The implication of the love scenes is that WALL-E is projecting the gender identities he saw in "Hello Dolly".
In Futurama the characters once met a rock alien whose species has only one sex (neuchachos). Finding the concept of physical sex incomprehensible, he administers a series of tests to see which one was best, eventually deciding that gender only causes division, so he takes away their sexual characteristics. In their neutral state, they find peace and harmony... until they realize they can't have sex ever again and demand their genitals back.