In one Mountain Dew commercial, a guy finds out his car remote can transform objects. Since he just broke up with his girlfriend, he conveniently uses it to turn his best friend into a hot girl. The implications of that commercial are very disturbing.
A series of Italian "Coloured is better" laundry commercials play this as a joke. The first has a woman throwing her pencil-necked white partner into the washing machine after he fails to seduce her, and he emerges as a sexy, muscled black man. The second has her partner throw her in after comparing her to models in a gentleman's magazine — and she emerges as a sexy, muscled black man.
There are thistwo commercials for Snickers, each featuring a rather cranky middle aged woman amongst a group of young men. Annoyed by her, they tell her that every time she gets hungry, she turns into a diva, and offer her a Snickers bar. After taking the first bite, it turns out that she is a young man too, who literally turned into a diva.
Anime & Manga
Ranma ½ is wholly built around Involuntary Shapeshifting, with the main character being an example of this trope. Both of Ranma's forms have their own Love Dodecahedron, though most pairings are unrequited. Particularly for the female "Ranma-chan", who has no interest in guys (because his mind stays that of a straight male).
Birdy the Mighty, in which the female title character has to share her body with a boy after she accidentally kills him. They are still discrete bodies, with Birdy able to switch them (and assume control over Tsutomu) at will. There is a short-lived exception to this, when Birdy receives heavy physical and mental trauma after a battle, and Tsutomu becomes the default personality, while stuck in Birdy's body.
In Kashimashi Girl Meets Girl, space aliens reanimate a shy, diminutive and sensitive Ordinary High School Student as a girl after they 'accidentally' crush him under their crashing spaceship. Unlike some other examples of this trope no "cure" is even possible so Hazumu stays a girl, and seems quite a bit happier that way.
Maze Megaburst Space is a complicated example. The title character changes gender at sunrise/sunset but each form has a separate personality and could almost be considered distinct individuals. The straightest example is when an artifact meant to lock the transition results in Male Maze inhabiting female Maze's body and vice versa come the next morning.
The Sailor Starlights from the final season of the anime—the manga has them as simple crossdressers. Just to clarify, they aren't "men who turn into women to fight" but "men who revert to being women to fight", everything points to them having been born female.
In the Sailor Moon manga, and its parent manga Codename: Sailor V, Usagi and Minako use their disguise devices to disguise themselves as men on a few occasions. It isn't clarified how far reaching this disguise magic is.
Naruto has a special technique called "Oiroke no Jutsu" (usually known in Western fandom as "Sexy no Jutsu" thanks to fan translations, officially translated by Viz as the "Sexy Jutsu"), used occasionally near the beginning of the series, where he temporarily turns into a cute, naked girl in order to give his opponents The Nose Bleed. It's stated that this is a "very easy technique" as the normal disguise technique is standard for any ninja (this one just transforms into a non-existent female); however, it's also a reference to the fact that Naruto has a kyuubi fox spirit within him. Traditionally, they had the power to shapeshift into beautiful human women. In the anime and manga he teaches the technique to the Third Hokage's grandson, and we later see the fruits of the training during the first couple of episodes/chapters of Naruto Shippuden. In the earlier editions of the Ultimate Ninja video game series, this is one of Naruto's special attacks. Users of the Sharingan technique can copy the special attacks of their opponents. The results are about as entertaining as you could imagine.
The Prince Of Tennis has special "chibi" episodes, where Fuji, Oishi, and Momoshiro are all female. (And Eiji's a cat, to boot.)
Tenshi Na Konamaiki: A a mischievous spirit twists Megumi's wish to be a "man among men" and turns him into a beautiful girl instead. Nobody except Megumi and her best friend remember she was ever male. It's eventually revealed that she'd been a girl all along and the spirit had hypnotized them into believing she'd once been male because he lacked the power to actually change her sex.
Everyone in the world of Simoun is born female, and doesn't commit to a permanent sex until age 17.
Cinderella Boy is about two detectives (a man and a woman) who are badly injured in a car accident and put back together in the same body by an ambiguous doctor—they switch places with each other at the stroke of midnight, with the twist that neither one can remember what the other did while in control of the body.
The Vision Of Escaflowne: Allen Schezar's long-lost sister Celena isn't so much lost as "transformed by lunatic Emperor Donkirk into Ax Crazy antagonist Dilandau".
A case of a voluntary gender bender is Kuugen Tenkou in Wagaya No Oinari Sama. Kuu can be either female or male and is comfortable in either form. This is because Kuu lived for so long s/he forgot what gender s/he was, and being a fox spirit, can change at will. Kuu seems to prefer female form, though.
One episode of The Tower of Druaga: The Aegis of Uruk had the entire main party switch genders as a result of a magical trap. Ahmey and Kaaya in particular found the experience quite distressing, as they were unaccustomed to walking with the, er, alteration in body balance.
Yu-Gi-Oh! GX: Yubel seems to self-identify as female but is a hermaphrodite, with the Japanese version possessing a male voice about half the time. Further complicating issues are the fact that in the past lives of Yubel and Judai, they were apparently both male.
Futaba-kun Change! has a rather unfortunate scenario. The title character's entire family changes sex whenever they get sexually aroused, which means a) he will have to be the "girl" in any future relationship and b) the person he always thought of as his father is actually his mother.
Pretty Face is about someone whose face was constructed to look like a girl's, but still remained physically male (except for some fake breasts that he occasionally uses).
Cute X Guy follows the life of Sumi Takaoko, a girl whose father promises her a serum he concocted will make her mature looking and sexy. She uses it because she hears that's the type of woman her crush likes; sadly, her eccentric dad neglected to tell her that it will make her a mature and sexyman. One she turns into whenever her heart rate increases, which happens all too often when she's near her crush. She goes on to make friends with several guys who turn into girls, all with different triggers.
Vampire Doll (with the added subtitle of Guilt-Na-Zan in the west) is a Gender Bender story about a vampire aristocrat called Guilt-Na-Zan who was vanquished many years ago and later brought back by the descendant of the man who offed him. Because the descendant is a perv with a Moe obsession, he brought Guilt-Na-Zan back in the form of a cute teenage girl by placing the vampire's soul into a wax doll, Guilt-Na-chan. Guilt-Na-chan can become Guilt-Na-Zan for brief periods when (s)he drinks the blood of the girl Guilt-Na-chan was modeled on (the resurrector's little sister, which implies he has a crush on his sister).
The second half of the manga Gacha Gacha, Gacha Gacha Secret (volume six and onward) has a malfunctioning virtual-reality pod turn a guy into the game's female instructor whenever he sneezes. Unlike most henever even triesto reverse it, and instead becomes friends with the girl he likes to get to know her better and get closer to her as a guy. Towards the end, the game's developers get him to try to cure it, as—per the manga's approach to science—each switch causes reversible (but fatal without treatment) brain damage.
In the Cute Witch series Ultra Maniac, this is the first major spell we see Nina cast. Ayu needed to beat Hiroki in a tennis match as the girls' and boys' tennis clubs were feuding over the use of the school tennis courts and had bet on a match between the two. So when Ayu says she could use a spell to make her strong, Nina casts a Gender Bender spell without thinking much. While Ayu was able to pass herself of as her own cousin all the spell did was throw Ayu's balance and timing off because of the size and strength difference. Later Nina and Ayu both use the spell because of mildly convoluted reasons surrounding a triple date.
Lala designed a rocket to improve women's physical appearance, but Rito landed on it. When the rocket exploded, Rito changed into a girl.
Afterwards, Lala creates a Transformation Ray for the express purpose of doing this, except with that he'll eventually turn back on his own. She uses it at least 4 times, usually so that Rito/Riko can go on a date with his male best friend. He obliges once, but whenever she tries it again, he runs.
Akane Chan Overdrive is a short, humorous ecchi manga where the main character, Amamiya, gets knocked unconscious and then sucked into the body of an attractive high school girl (Akane). Later in the story Amamiya manages to return to his own body, but his best friend Murai is then sucked into Akane's body. Amamiya proceeds to propose marriage.
"Miracle Worker" Emporio Ivankov is a man who ate the Horu-Horu Fruit, which allows him to affect the hormones in a person's body, to the point where a man can become a woman and a woman can become a man, with Ivankov refusing to say which of the Newkama were altered and which weren't.
An April Fools joke made by some people created a page in which Luffy was a girl because of Ivankov, mainly to disguise himself.
There's also Bentham (Mr 2 Bon Kurei) who ate the Mane Mane no Mi, which allows him to transform into anybody he's ever touched.
Yuuri in Tayutama has a magic charm that can turn him into a girl, mostly used for infiltrating Flawless Girls' School for purposes that are honestly good. As long as he doesn't make a habit out of it.
In the first season of Ojamajo Doremi, the girls once use their magic to turn into boys, in order to investigate in their stolen Magic-Shop. Doremi, however, blew the cover by chanting her Catch Phrase ("I'm the unluckiest pretty Girl in the whole world!!") upon seeing magic charms who are claimed to be able to prevent said Catch Phrase.
Boku no Shotaiken is perhaps the Ur-example of Gender Bender Manga: After a partially successful suicide attempt the main character has his brain transplanted in the body of a young woman. He then goes back to school seeking vengeance on the girls who drove him to jump off the cliff in the first place, only to strike up a Gender Bender Friendship with his old crush instead.
In Kampfer, Natsuru Senou, the (originally) male lead character, transforms into a girl whenever he becomes a Kämpfer whether he wants to or not.
The premise of Kedamono Damono revolves around this: the main character's boyfriend, Haruki, turns into a lascivious girl at night. Naturally, it involves some Bi the Way.
Homura in Sekirei had an unstable sex, and so started turning into a woman in response to the main character. It's not been revealed if the transformation was complete or not, but Homura now has a more feminine body and face as well as breasts.
In Heaven's Lost Property, through some Applied Phlebotinum, protagonist Tomoki transforms himself into "Tomoko", his female identity. After gaining the trust of the school by acting like the anime girls he's familiar with, his main objective becomes clear: to get into the baths with the girls and get intimate under the pretense of "we're all girls, aren't we?". His plan nearly succeeds, if he hadn't succumbed to the excitement of it all. He uses the transformation again in the second season; since everybody knows what "Tomoko" looks like, she decides to use another Applied Phlebotinum to turn herself into swimming pool water (to grope the girls in it, of course). After she is found out and transforms back into her girl body, she runs into the girls bathroom, where she is trapped in one of the stalls. Rather than go out and get beaten up by the girls, she instead flushes herself down the toilet.
Kenzo in Blue Drop: Tenshi no Bokura has been turned into a girl by aliens intent on conducting sexual experiments on human beings. He/she is supposed to get impregnated, and chooses his/her best friend Shouta as a partner.
A chapter features all of the main characters (as well as some other weapons and masters) being gender flipped. In context, they were experiencing the Seven Deadly Sins. In the Lust area, they became their own versions of lust. For example, Tsubaki is a tall Bishōnen, Maka is a straight-laced male student, Soul is a very stylish and feminine woman (Soul admits that he makes up his usual slacker look to look cool), and Black☆Star has an impressive chest (What other size would a person that loves attention that much have?). It's also worth noting that the twist of them being their own ideal sexualization has interesting ramifications for shippers. While Black☆Star is not quite the bishonen that Tsubaki is pinning for, he is certainly working his way towards it and Tsubaki certainly has the one ahem... aspect that Black☆Star seems obsessed with. However it is almost pathetically obvious with Soul Eater himself, whose ideal woman just happens to be the elegant small-chested woman that his "excitement" transforms Maka into.
The two-chapter manga Kanaete Aizen tells the story of a young man who desperately wants a girlfriend. However, with the exception of his childhood friend, who he sees more of as a friend than a girl, he can't even talk to a girl without going into a full-blown panic attack. One night, he wishes on a temple charm for a cute girl of his very own, only to wake up the next morning to find out the spirit of the charm granted his wish by turning him into a girl. Going to school as his "cousin", he, well you should be ableto figure out the rest.
Played for angst with Ranmaru of the manga series Kagerou Nostalgia. Formerly a woman, Ran was transformed into a man by the series' Big Bad before the story even began and now serves as one of his two Dragons. This sucks for her partner, Rikimaru who had a huge crush on her female form. And did we mention that they're now forced to serve together as Heterosexual Life Partners? And that once a month she changes back to a woman? And that fifteen years ago he told her how he felt and pretty much destroyed their relationship? As previously stated, it's played entirely for angst.
In the manga Aragami Hime, the female protagonist Kazuki is the reincarnation of Akoumaru, who is a male in her past life. The reason behind this is because Akoumaru wanted to become the Aragami Hime, which led to the main plot of the story. Though this became a huge blessing for the male protagonist Shirou in the ending. The same goes for Kazuki's brother, Masaki, who was a female as well as Akoumaru's lover in his past life.
Yona Rouma, the protagonist of Sekainohate De Aimashou, gets turned into a woman when Emillio slips him a potion while unconscious. Rouma gets turned into a female in order to be Emillio's wife, much to Rouma's dismay.
In the second season of Seikon No Qwaser, Alexander Nikolaevich Her infiltrates an all-girls school, having to crossdress to do so. Normal so far, until the girls enter a virtual reality program that causes their thoughts to manifest in the program. When Alexander enters the program, he quickly realizes that his perverted thoughts have given him some...extra parts of anatomy.
In chapter 37 of the manga, a magic spell briefly turns the male protagonist Takeru and his friend Kengo into girls. But they are drunk at the time and don't recall anything about the experience.
Syria has the power to reverse things. Such as being a guy.
In Sorcerer Stabber Orphen, we have a combination of Gender Bender and Transsexual in the local Cool Big Sis and Orphen's first travel partner, Stephanie. Orphen explains to Majik and Cleao that she used to be a male magic-user named Stephan until few years ago, when she was seriously injured and her male body was horribly torn apart. During her recovery, she asked the healers if they could turn said male body into a female one; they accepted, and now Stephanie has a female body that she's very comfortable with.
Ohiri from Gestalt. Not revealed in the OAV, but in the last volume of the manga, Ohiri is a false body & she's actually a male god.
In Asuka Hybrid, Asuka got magically turned into a girl by a mystery woman and a misinterpreted wish.
The protagonist Eita Chinami from Idol Pretender gets turned into a girl overnight when he mistook the "female beauty" pills as cold medicine. The story centers around Chinami becoming an idol, trying to earn lots of money to purchase the same pills in order to change himself back.
The main concept of Bokura No Kiseki centers around the fact that the male protagonist, Harusumi, is the Reincarnation of a princess, Veronica. That being said, the series contains surprisingly little in the way of gender-bending antics. Hiroki, a female character, ends up being the reincarnation of a male squire.
Yamada-kun to 7-nin no Majo features some amusing Gender Bending comedy. Yamda as someone with the power to swap bodies spends a fair amount of time as a girl. He's admitted he had to go to the toilet "like a girl" (Shirashi meanwhile just avoids going to the toilet while she's a boy). Regardless of whether he is a boy or a girl Yamada will tend to stomp around like he's carrying bowling balls and show little regard for flashing people when giving roundhouse kicks. Which is probably part of the reason why Yamada's attempts to use feminine wiles to his advantage usually don't work out well.
In Gintama, there is an entire arc centered around this trope. It starts off with Kyuubei talking to a fortune-teller who then changes the gender of the entire Kabukichou residents.
Rosario Vampire features a one-shot doppleganger villain that turns into Tsukune in order to sneak off of the school's property without getting caught. It ends up getting caught by Tsukune's entire harem, who start fighting over "him"; when he hits Rose, she gets aroused, which causes Yukari to demonstrate her favorite fetish. Perhaps now is a good time to mention that the doppleganger is terrified of women, though it's never mentioned why. Tsukune ends up showing up and starts using his powers, whipping him into a mindless rage. The doppleganger grabs Kurumu to steal her succubus powers and ends up turning into a girl complete with Kurumu's G-cup breasts, which it flashes Tsukune with to distract him; it works very well. Kurumu ends up being extremely upset about how the doppleganger is acting with "her" body. Considering that the doppleganger is wearing a bra when it rips open its shirt (which it stole from Tsukune to better disguise itself as him) in front of Tsukune, no one quite knows which form was actually the gender-bent one.
After cross dressing as a girl throughout the 2nd half of the story, Cruz finally got turned into a girl by Blade in chapter 113 of Needless. The expression on Disc's face towards this is priceless.
Munchkin includes at least one Gender Bender card in each iteration, and sometimes two! (Might come in handy if you're a low-level and poorly-geared male facing a deadly Amazon!)
In Ultimate Spider-Man, Jessica Drew, Spider-Woman, is the end result of the Ultimate Clone Saga. She is a clone of Peter Parker, implanted with his memories and genetically modified in vitro to be female and develop additional powers. During the Clone Saga she fills the same role as Ben Riley did in the 616 Clone Saga. Afterwards she assumed the CIA/FBI created identity of Jessica Drew and returned to active crime fighting as Spider-Woman. She confessed that along with inheriting Peter's memories, she is still in love with Mary Jane Watson.
Supporting character Courier has the power of complete control of his body's cells, allowing for shapeshifting as well as other abilities. While undercover as a woman, he was discovered by Mr. Sinister and injected with drugs that would cause his body to break down. Gambit made a deal with Sinister to have Courier stabilized, and Sinister kept up his end of the bargain — but didn't know Courier was originally male. The female form is now Courier's default form.
Due to a consciousness transfer to a cloned body gone slightly askew, Sinister himself is now Miss Sinister.
Alpha Flight member Walter Langkowski spent several years as "Wanda," due to having possessed a dead female teammate's body.
Iron Man is even subjected to this; his armor (which, at this point, is partially fused with his body) gets hijacked by Ultron and reshaped into the image of Janet van Dyne, Ultron's "mother". After it's undone, the entire Mighty Avengers team teases him about it.
The Skrulls from the Marvel Universe are a race of shapeshifters. Skrulls changing into other genders have been seen from their very first appearance (the four Skrulls that attempted to replace the Fantastic Four were all male). It's just that nobody had noticed the detail or thought on it until the example below.
One obvious application of the Skulls' inherent ability didn't come to light (at least, in canon) until the male Skrull Xavin turned up in Runaways and asked for Karolina's hand in marriage. Karolina, being a lesbian, refused... until Xavin transformed into a female human, because for a Skrull to change his/her physical sex is as easy as blinking. Later, when Xavin and Karolina returned to Earth, Xavin turned out to be less comfortable with the transformation than s/he had first claimed... It seems that during Joss Whedon's run on the series Xavin finally accepted femininity. Although, being a Skrull, he/she did continue to shapeshift as occasion and whim permitted, Xavin referred to male forms as being "false". Interestingly, when Terry Moore took over the series we saw Xavin assume a female Skrull form for the first time, perhaps indicating his/her deeper level of comfort with the whole thing. The issue of whether Skrulls even have set gender identities and, if so, whether it's common to attempt to change like this, has been left ambiguous.
Loki of The Mighty Thor spent some time in a female body (eventually revealed to be that of the goddess Sif); he eventually returned to his usual body, though as in the original Norse mythology, his sorcery also allows him to turn into a woman whenever he feels like it, which he has done on a few occasions.
Invoked in Captain America storyline, "The Superia Stratagem". Supervillain Superia plans to establish "Femizonia" — a female-ruled utopia from which she will Take Over the World. Captain America and his allies infiltrate her base to stop her, but Cap and Paladin are captured at one point, and subjected to Superia's feminization process. (She believes that, as women, the heroes will see the light and join her cause.) The two male heroes are rescued before the process does anything to them, however.
In Shade, the Changing Man, Shade's consciousness leaps into the body of a recently murdered woman. Unfortunately, he was unable to alter her body to resemble his old one until he solved her murder and put her soul at rest. This led to various comical scenes with Shade experiencing the Male Gaze, his first period and sex as a woman.
The second Infinity, Inc.. series, from the writer of Shade, Peter Milligan, featured team member Fury, who involuntarily switches between genders.
In Resurrection Man, title character Mitch Shelley spends a couple of issues as a woman, after being tortured to death several times (with each time being more painful than the last). His persecutor has a theory (opinions differ as to the amount of Truth in Television therein):
Mr. Bland: Women have appreciably higher pain thresholds than men. If Shelley reconfigures from each termination in a form suited to "protect" him from that method of death, then a female version would make sense.
In one issue of Guy Gardner: Warrior, the title character's demonic archenemy Dementor turns him into a woman ("Gal Gardner") for no clear reason. (It would be highly cynical to suggest that the real reason was that, at the time, Guy was a rare example of a male character in a Stripperiffic costume, so naturally they wanted to show what it looked like on a female character.)
Played for Drama in an infamous Retcon that long-time supporting character Shvaughn Erin had been taking the gender-changing drug "ProFem" the entire time we'd known her. After going off the drug, she becomes "Sean."
"Grandin Gender Reversal Disease" causes a temporary change of gender. It temporarily transforms Matter-Eater Lad into Matter-Eater Lass as part of an infiltration mission.
Played for Laughs in a very silly Legion of Substitute Heroes one-shot, when Color Kid becomes Color Queen.
Averted/Misdiagnosed once by Ambush Bug in an issue of Supergirl. The Bug spends most of the story trying to cure Superman of the dastardly plot that transformed him into a young blonde woman. It's a case of Critical Research Failure for Ambush Bug, though. Despite his Genre Savviness, he somehow was completely unaware of the existence of SuperGIRL. He does, however, turn out to be Genre Savvy enough to figure out Supergirl's secret identity at the end.note Supergirl (2nd Series) #16 (1984)
Zatanna's beautiful assistant Mikey is the result of an unspecified magical Gender Bender. A "three years ago" dream sequence, depicts her as a burly male.note Zatanna #13 (2011)Word of God from writer Paul Dini says "Zatanna didn't do it & can't reverse it; Mikey brought it on him/herself. Now Mikey's in an interesting place where she has to sort out her feelings about this." While there's a lot more to Mikey's story, with the book's cancellation, it doesn't seem likely that the story will be told any time soon, if ever.
In a 1960 Superboy story, "Claire Kent: Super-Sister," Superboy is turned into a girl by a telepathic alien girl from a matriarchal planet who's insulted by Superboy's chauvinistic thoughts. Superboy has to adjust to being a girl in both his secret and super identities... but in the end, it turns out to be All Just a Dream.note Superboy #78 (1960)
Believe it or not, Superboy's dog, Krypto, had not one, but two Red Kryptonite Gender Bender adventures!
"The Handsome Hound of Steel" has a plot that wouldn't be at all out of place in modern TG fiction. Krypto wants to change into a handsome collie to impress a female collie, but a Red K cloud ends up turning Krypto into a duplicate of the bitch he fancies — and it turns out she's pregnant! Krypto actually delivers puppies in his altered form (though they vanish from existence when he changes back to normal.)note Superboy #101 (1962)
In "Krypto's Three Amazing Transformations", a time-traveling Krypto gets turned into a cow (and definitely a female, because she gets milked!) And not just any cow, but the cow that started the great Chicago fire of 1871! (As it happens, the wrongly accused Mrs. O'Leary's cow was innocently grazing in a pasture at the time.)note Superman Family #165 ( 1974)
Given its premise (a dial that transforms its user into a random superheroic identity), you'd think this trope would have turned up in Dial H For Hero more often than this:
In the Chris King/Vicki Grant series, it showed up once, albeit in circuitous fashion. The dial turned Chris into a hero named "Any-Body" — a hero with shapeshifting powers that Chris used to take the form of Naiad, a villainess, in order to trick another bad guy.
One storyline in the 2003-2005 H.E.R.O. revival had a chauvinistic male character use the dial, after which he turned into a buxom blonde female hero. Unfortunately he had no means of changing himself back. The story was not played for laughs, and included such low points as the hero being date-raped by his male best friend.
The New 52's Dial H series introduces this concept in the third issue, when the main character learns he'll land in a female body "every few dials."
Lucifer, in Joseph Michael Linsner's Dawn series, has been shown at least once to be able to take on a female form. Considering he is a former angel and the gay lover of Ahura Mazda (the series' God analogue), this has some interesting potential ramifications.
At the end of the XXXenophile story "Vici, Vidi, Veni", an invading army is turned into frogs by a god they have angered. The sole survivor (who was in the god's temple at the time) announces that he believes in the god and is promptly turned into a woman and made an acolyte of the god, being led off to the novice quarters (and, implicitly, hot lesbian sex).
In the comic book Mantra from Malibu Publishing, the main character is a warrior employed by a wizard. He's continually reborn by having the wizard transplant his soul into a new male host whenever he died. At the start of the series, the wizard is betrayed and has only enough strength to move his most loyal warrior's soul one more time. He tells the warrior that this time it will be different. The warrior awakes to find himself in the body of a single mother. The series deals with him coping with this and having to learn magic to cope with his lack of martial abilities.
In Camelot 3000 by Mike W. Barr and Brian Bolland, King Arthur is awakened from his sleep during an alien invasion. A number of Arthur's knights have been reincarnated, sometimes into distinctly different bodies (e.g., black, Asian, hideous mutant.) Sir Tristan, quite a womanizer in his former life, is reincarnated as a young woman. The appearance of Isolde (also reincarnated, but still female) complicates the matter further, although they end up in a surprisingly sweet lesbian relationship.
When IDW comics started their Transformers comic, it was decided that there would only be male Cybertronians. When they decided to include female transformer Arcee into the universe, they decided not to retcon their decision, and so they made Arcee the victim of a forced alteration by a Mad Scientist specifically to introduce gender to the race. She's understandably pissed off about it.
In The Sandman, Desire can be either gender whenever it wants to be, and is frequently depicted with both male and female traits. In its first appearance, Desire greatly resembles another being who is "whatever it wants to be": Gozer from Ghostbusters.
In Alan Moore's Promethea, Roger, a member of the supporting character team "the Five Swell Guys". Roger used to be a man until an unseen incident at "Suffragette City" turned him into a woman. Roger's original form was never depicted in the comic.
Mighty Man of The Savage Dragon is an ancient entity passed from host to host at the point of death. The current host is female Ann Stevens (or New Ann...it's complicated) - the host, regardless of their sex, is able to transform into a tall blonde man with Flying Brick powers, by tapping their wrists together.
In the Archie Comics story "The Great Switcheroo", Sabrina the Teenage Witch's cat Salem casts a spell that changes the sex of everybody in Riverdale. The story plays a bit like a Gender Flip in execution, as none of the transformed characters know what their "true" sex is supposed to be, but it "really" happened, and Sabrina's eventual reversal spell isn't actually a Reset Button. There's even video evidence suggesting that the gang spent a day as the opposite sex, though none of them remember it.note Archie #636 (2012)
In the 2012 relaunch of Youngblood, Photon, formerly a male character, is now Lady Photon. His/her race apparently switches genders every seven years.
Shermans Lagoon has Filmore the sea turtle turn into a female for a while in an early arc. Then he turns back.
In the Albanian story The Girl Who Became a Boy, uh...well, Exactly What It Says on the Tin. Similar to Mulan, a girl pretends to be a boy to give her family honor. After adventures and even getting married, she gets cursed into changing gender. This is surprisingly congruent with Albanian culture. The practice is dwindling now, but Albanian girls would swear themselves to celibacy and be considered men socially. This was often done to make sure there would be a "male" head of the household.
An odd bit of folklore claims that kissing one's own elbow will cause a person to change sexes. (Did you just try it? It works!) No it doesn't - it's impossible to kiss one's own elbow. And before anyone asks, it wouldn't work if your arm isn't connected to your body.
There are several fan-written sequels to the "Claire Kent: Super-Sister" Superboy comic book story (see above). In these stories, Clark's transformation into Claire is notAll Just a Dream. The first story in the series can be read on this Website.
In  Blessing In Disguise, a Spider-Man fanfic, the radioactive spider who bites Peter Parker is female, which results in Peter not only gaining spider powers, but turning into a girl.
Blue Belle, a Buffy the Vampire Slayer crossover with the Marvel Universe, in which a Halloween costume sticks Xander with Mystique's powers and base form, and an inability to resume his own appearance... so he morphs into Willow, and poses as her cousin.
iFight Crime With Victorious, an iCarly fanfic, has a character who is able to switch the genders of any character they come in contact with. This leads to an interesting conflict with the protagonists when after the gender-switching bad guy is defeated, they are unable to change their genders back.
While uncommon, Thor fanfics where Loki turns into a woman are not too hard to find. It’s usually explained by the fact that he’s a frost giant and inspired by Norse myths of the gender-changing god (see the "Norse" entry in the "Mythology" tab). (All) Father Loki is one such fic.
Films — Live-Action
The 1940 Hal Roach feature Turnabout concerns a bickering husband and wife, each of whom wishes they could have the "easy" life of the other gender. Their wish is subsequently granted by an enchanted Indian sculpture sitting on their mantelpiece. By the end of the film things are seemingly back to normal... until the Indian god confesses that he screwed up and informs the husband that he's now pregnant. The film was an adaptation of Thorne Smith's 1931 novel, which was later adapted as a short-lived TV series in 1978.
Zerophilia, directed by Martin Curland, concerns a young man named Luke who obtains the rare Z chromosome after a sexual encounter with a mysterious woman which turns him into a zerophiliac, a person whose sex changes with the act of sex (either by your lonesome or with another person). Sex with another zerophile induces mode locking.
The obscure spoof Dr Heckyl And Mr Hype puts the doctor through a number of transformations, including one where he becomes a woman.
In the sex comedy Sexual Chemistry, a chemist's attempt to create a sex-enhancing drug backfires, turning him into a woman. He keeps changing back and forth over the course of the movie. Hilarity Ensues.
Something Special (a.k.a. Willy/Milly) is a rare female-to-male example, where a tomboyish teenager wakes up to find herself magically transformed into a male after making a wish during a solar eclipse.
In Splice, Ginger, one of the two transgenic creatures created by Clive and Elsa, turns from female to male due to hormonal changes, and fights Fred (the other transgenic creature, who was male from the start) during a press conference that unleashes a shower of blood on the front row. This turns out to be foreshadowing for similar changes in Dren.
In Jurassic Park, the all-female dinosaur population gradually has some of them turn male. This is due to the dino DNA that created them being mixed with the DNA of a frog species that can change gender.
The Hong Kong action comedy Holy Weapon features this towards the end. In the movie, Ghost Doctor creates "Feminine Wine" for an intersexed woman, warning that if a man drinks even just a drop, he'd become a woman. They then have the male Idiot Hero Ng Tung look after the brew without telling him what it is or what it does. Ng Tung unwittingly drinks the brew, thinking it's a nutritious soup. Then his penis tells him that from now on, whenever his body gets wet, he'll turn into a woman. He'll become a man again when he dries his body. This becomes useful during the final battle, when the Big Bad's Mooks throw Ng Tung into the river as a sacrifice, only for him to emerge fully female, complete with Gainaxing and Girlish Pigtails. Thus, he/she becomes the Seven Virgins' Eleventh Hour Ranger (since one of them is trapped in a net throughout the battle).
In The Gamers: Dorkness Rising, Luster is constantly switching between female and male due to her player forgetting and being reminded of her true gender. It's lampshaded several times, both in-character and out-of-character.
In Frankenstein Created Woman, Doctor Frankenstein successfully transfers the soul of a man into the just-drowned body of a deformed young woman. Frankenstein fixes up the woman's body, making her beautiful, but as with most of the Doctor's experiments, things start going downhill from there.
In the movie Scooby Doo, the gang's souls switch bodies at one point, causing Fred, in Daphne's boyd, to remark "Hey, I can look at myself naked!" Daphne was not amused.
In the sequel, Scooby Doo Monsters Unleashed, Shaggy drinks an unknown potion and transforms (from the neck down) into a woman, for a little while.
The Australian feature Dating the Enemy takes the classic set up of a bickering couple who get an opportunity (in a Freaky Friday Flip) to "see the world through the other's eyes".
In Gozu, a dead Yakuza brother returns as a young attractive woman with no explanation given why.
The premise of the Sex Gates trilogy by Darrell Bain & Jeanine Berry: Portals appear at random all over the world. If they don't make you vanish when you pass through them, they cause you to emerge as a flawlessly healthy 18-year-old... of the opposite gender. Hilarity Ensues. Well, not so much hilarity as extreme societal upheaval. The Middle Eastern response — namely, chucking various imams and abusive husbands through, was highlyamusing. Other aspects, like the Trans Equals Gay implications of homosexuals lining up for their Gender Bender or women eager for the chance to be the "superior" sex, may be less amusing.
In Iain Banks' Culture novels, citizens of the Culture are able to change their gender at will. The process is slow, taking several months, but is done entirely using consciously-released hormone, not requiring any external assistance. The change is so complete that they begin to produce the appropriate sex cells, and a newly-female person can get pregnant and give birth. Most people in the Culture will spend a year or two as the opposite sex at some point in their lives, just to see what it's like. A popular expression of love is for a couple to conceive a child, then change gender and conceive another, so both partners are pregnant with the other's child at the same time (they are also able to temporarily arrest the development of the embryo/fetus, so that they can time it so they come to term together — if the embryo is only just conceived, they can even keep it alive while they become male).
In Gael Baudino's Dragon trilogy, an enemy wizard does this to an entire troop of soldiers from an extremely sexist country. The transformation is permanent, and the characters' adaptation to their new state is dealt with at length; the new women's situations are dealt with with surprising sensitivity, given that at the time Baudino was a Dianic Wiccan.
Princess Ozma of L. Frank Baum's Oz series was magically changed into a boy as a baby, and grew up this way (under the name "Tip") until the spell was discovered and she was changed back. The fact that their personalities are total opposites has led to at least a century of many fans trying to explain this away via either Fan Dis Continuity or Retcon. Lampshaded when the Gump mentions he thought Ozma was nicer when she was a boy. The Gump also mentions that Ozma didn't much like him talking since she changed her name.
A Civil Campaign has, as a significant character, Lord Dono Vorrutyer... formerly Lady Donna Vorrutyer.
Not to mention Bel Thorne the hermaphrodite, who, while technically both male and female, is quite fond of switching its perceived gender around just to mess with people's heads.
A common motif in Jack L. Chalker books. Usually it's a) to show just how indomitable the transformed character is, and b) to showcase the sheer evil of the individuals responsible... and make their eventual Karmic Deaths—or at least karmic comeuppance — all the more appropriate. Appropriately enough given how deeply Chalker is associated with this trope, his immortal hero Nathan Brazil's last act in Chalker's final book is to "accidentally" inflict a Gender Bender on himself; it may have been a Freudian Slip on the character's part.
In Stardust, Bernard the goat herder is first turned into a goat by the Big Bad, and later into a woman to pose as her daughter.
The short story "Changes" has Gender Bending as its premise, as a cancer cure called Reboot that works by altering the patients DNA has the side-effect of transforming the patient into a fully functional and fertile member of the opposite gender. The story takes place over several decades, analyzing how society would react to the effects introduced by such a drug. The middle eastern response is especially horrific, in contrast to the Sex Gates example above.
The entire basis of the plot of James Alan Gardner's novel Commitment Hour.
This is the ending twist of the Clive Barker short story "The Madonna" from The Books of Blood. All men who enter The Madonna's lair become women. Though it can be terrifying for some people, he/she ended up better than mostother characters.
An important point in Charles Stross' Glasshouse is that the characters come from a society where Gender Benders are ridiculously easy. It's implied that most people tend to settle on a particular gender for the sake of convenience; the protagonist is usually male, but doesn't even remember what his original body's gender was.
The middle part of The Making of a Mage is basically "The Making of a Priestess". When Elminster agreed to serve the goddess of magic, he finds himself teleported without any warning to an unknown location and turned into a lass — "to see the world through the eyes of a woman" (and to hide him from Magelords out for his blood), having nothing on her save half of broken ancestral sword, and no magic abilities save innate magic vision. Later he learned the spell himself. In the next book, Mystra pushes a silent sex-inverting spell into his mind, to give him a way to circumvent controls built into his body. Which he used while embraced... er... restrained by his current Love Interest, no less. "Well met. Call me Elmara, please!"
Several Animorphs characters do cross-gender human morphs. Marco morphs the female governor in one book, and presumably, Cassie and Rachel morph male when they acquire sailors for a mission on an aircraft carrier. Rachel's eagle, acquired between books 1 and 2, is male, as is the grizzly bear that she acquired in book 7. Marco acquires a girl wolf in book 3, while Jake, Marco and Ax all become a female skunk in book 9, and Rachel and Cassie (along with the four boys) acquire a male polar bear in book 25. Tobias acquires Taylor, a human female, in book 43.
This is the plot point of one book, where Visser Three morphs into a female human and masquerades as Tobias' cousin Aria in order to capture him after he is read a letter from his father, Prince Elfangor. Visser Three spends most of his time in this form during the book, just in case Tobias is morph-capable and spied on him in animal form; Tobias only figures out the trick because Visser Three is too good at acting like a human woman and checks "her" hair in a mirror, which is automatic for most women but not necessarily for one who's been living in Africa for years, which was what "Aria" was supposed to be doing for most of Tobias' life.
In The Wheel of Time, after Balthamel dies, he is resurrected as the beautiful woman, Aran'gar. This is situational irony, because Balthamel had been known as a tremendous lecher.
In the 1952 French short story Héloïse by Marcel Aymé, the thirty-five-year old Martin turns into the title female character on each evening, causing her to clash with his wife. Things get complicated when Martin falls in love with Héloïse, and when Héloïse gets out and sleeps with other men. At the end of the story, Martin's wife gives him out that Héloïse is pregnant; Martin/Héloïse will give birth to a boy who will soon turn into a girl. Ouch.
In the Chanur Novels, the trigendered Stsho change gender when "phasing" (a personality breakdown and reformation caused by emotional or physical trauma).
In Walter Jon Williams' Cyberpunk novel Hardwired, the rich elite often transfer their consciousness to a younger body to extend their lives. The book introduces one who used to be an elderly man but got himself transferred to a young, female body to live his sexual fantasies of submission and vulnerability. S/He gets what s/he asked for and more when Sarah, one of the protagonists seduces, and then murders him/her.
In the novel Cycler by Lauren McLaughlin, the main character Jill changes into a boy, Jack, before (or during) her period.
In the Safehold series by David Weber, Nimue Alban (or, specifically, the robot with Nimue Alban's personality) crafts the persona of Merlin Athrawes. Her robotic body has the capability to shift genders, which she uses to complete the image.
Pretty much the whole plot of Death's Master, the second novel in Tanith Lee's Flat Earth fantasy series. Lee also explores gender-switching in her Biting The Sun series, where changing bodies and genders is almost as easy as changing clothes. Officially you're only supposed to change once every thirty days, but nobody pays attention to that.
In Judith Tarr's Avaryan Rising series, a young nobleman from one nation is turned female—by way of a dangerous magic ritual—so that s/he can marry the prince of another nation for diplomatic reasons. Predictably, s/he's smokin' hawt in female form.
In Goblet of Fire, Barty Crouch, Jr. escaped Azkaban by swapping identities with his mother via Polyjuice Potion.
Deathly Hallows, in order to get Harry out of Privet Drive, five of his friends (and Mundungus Fletcher) disguise themselves as Harry using Polyjuice potion. Two of the decoy Harrys are Hermione and Fleur. Amusingly, Fleur isn't too happy about being Harry; after the transformation is complete, she tells Bill not to look at her because she's hideous.
In the Mercedes Lackey and Piers Anthony novel, If I Pay Thee Not In Gold, there be demons. They look ordinary, if beautiful, and with awesome eyes, but normal for normals where they come from. What distinguishes them is immortality... and gender bending when they have sex. Imagine losing your virginity and learning that. How can demons die? By being killed, or if a partner is unfaithful.
In Warrior Cats, the others often can't keep up with the massive cast, especially characters who were created just to flesh out the allegiances, so this has happened to several characters (most notably Sedgewhisker and Rowanclaw).
In Dread Brass Shadows, Garrett encounters a couple of characters who magically disguise themselves as other people, sometimes of the opposite sex. Finding the corpse of one of them, he's squicked out to discover that the dead man is reverting from his assumed female form to his natural one only gradually, from top to bottom.
In Sphere, the protagonist tests out his reality-warping abilities on some nearby mummified corpses, changing men to women and women to men. That's right: gender-bending corpses.
In Cordwainer Smith's Instrumentality short story, "The Crime and the Glory of Commander Suzdal," the Arachosians made their women into man-like things (klopts) on purpose. It was a Fate Worse Than Death.
In Peter Pan in Scarlet, the former Lost Boys must wear their children's clothing in order to become children again and return to Neverland. Unfortunately for Tootles, he has no sons, so must wear his daughter's ballet dress, and turns into a girl.
A... rather awkward version happens in Galaxy Of Fear: The Brain Spiders. Jabba the Hutt has a weird gambit going where he removes the brains of major criminals, turns their bodies in for the reward money, and installs their brains into the bodies of hapless people in his fortress - their brains end up in spider droids, which sucks. A particularly large and brutish killer's intended body is set free, so he gets put into Tash Arranda, a not-yet-fourteen-year-old girl. At first he doesn't mind much, but soon he starts complaining to Jabba about it. Jabba is just amused. The narration, once the point of view character figures it out, calls him "he".
In A Song of Ice and Fire Dragons are described by Maester Aemon as "neither male nor female, [...] but now one and now the other, as changeable as flame."
Delenn from Babylon 5 was originally supposed to have been male or neuter in the first season, before entering the chrysalis and becoming female, but the idea was dropped. Sources differ as to whether the exact reason was one of these, or perhaps a combination:
They couldn't get Mira Furlan's (electronically altered) voice as "Male Delenn" quite right.
Furlan refused to play Delenn as a male.
They did use this idea in the original pilot as aired, but dropped it for the series and later rebroadcasts of the pilot have Mira Furlan's unaltered voice. Unfortunately, there's nothing that can reasonably be done about the Male Delenn makeup (which looks remarkably like the original G'Kar makeup, particularly noticeable in their scenes together).
Later that same season, Willow was cursed with a Glamour that caused her to take on Warren's note (the man responsible for the death of her first girlfriend, Tara) appearance after she shared a kiss with her new girlfriend. The curse started as an illusion, but the longer Willow looked like Warren, the more his personality began to overtake her own — eventually causing her to try to recreate his attack on Buffy.
The 1998 version of Fantasy Island has the episode "Estrogen," in which a man asks Mr. Rourke to give him a better understanding of women. Guess what happens.
In Heroes, guess what's the first thing Sylar turns into after getting the ability to transform?
In a minor example, Dax by way of The Nth Doctor. She's female through both incarnations in the main series, but Sisko (who knew her before the current incarnation) calls her "old man" (despite appearing to be a young woman). One of her male forms is seen in a flashback, and others are seen through a psychic-body-swap-thing, including one of her previous female forms in a male host.
In another episode, Quark (for reasons having to do with a Ferengi diplomat) has to have a temporary sex change. Not only does he pop out of Sickbay as a physiologically-complete Ferengi woman, his personality has suddenly altered to be completely feminine. Cue the parade of human female stereotype behaviors.
During an espionage mission against the Dominion, Odo (a shapeshifter) briefly assumes the form of the Female Changeling.
A fake ad for something called For Men Only (a parody of men's haircare products) showcases a liquid that turns men into women. There are several male to female morphs in it, including one of Jay himself using the product.
Another episode has Jay in drag (a supermodel with his voice).
On the episode where Pam Anderson is the guest, Jay asks several questions about implants and then asks her.."If you could be a man, who would it be?" Pam responds "I could be you!" Jay then exclaims "That's perfect. Why?" Pam's answer is "So I could sit there, torturing you, asking about your implants."
Doctor Who has used this trope a couple times, at least in the context of the title character's potential regeneration as a woman:
In "The Curse of Fatal Death"; an Affectionate Parody created for the 1999 Comic Relief appeal night, the Doctor cycles through all of his remaining regenerations in quick succession, with the final one being Joanna Lumley. The Doctor's female companion (who was engaged to him) is understandably rather disturbed; his arch-nemesis, the Master, somewhat less so. The former enemies walk off arm in arm.
The episode "The Doctor's Wife" from the actual series revealed that it's indeed possible for a Time Lord to regenerate as the opposite sex (assuming the Doctor wasn't joking):
Doctor: See that snake? The mark of the Corsair. Fantastic bloke. He had that snake as a tattoo in every regeneration. Didn't feel like himself unless he had the tattoo... or herself a couple of times. Oh hoo, she was a bad girl!
Neil Gaiman (who wrote the episode) also mentions the Corsair having a couple of female regenerations in The Brilliant Book 2012.
Zig-zagged in the episode "New Earth": the villainous Cassandra (a transwoman from the future who has surgically altered her body so many times that only her eyes and a flap of skin remain) possesses the body of companion Rose Tyler; when the Doctor orders Cassandra to leave Rose's body, she complies...by transferring herself into his body. Cassandra is amused by her newfound maleness, reveling in her handsome figure and new "parts" ("And hardly used!"). However, circumstances force her to abandon the Doctor's body, and she spends the rest of the episode jumping between numerous female hosts before settling on the body of her cloned male servant.
In the French TV series Vice Versa, due to a lab accident the main character Thomas turns into his female self Emmanuelle (then Julia, in season two) whenever he hits his elbow.
An episode of Tomica Hero Rescue Force has the Big Bad, inspired by the sex changing ability of clownfish (see the fish example under "Other"), create a virus to turn all men into women, thus robbing humanity of their ability to reproduce, and eventually causing our extinction. She's stopped, naturally, but not before she manages to transform the male heroes.
In one episode of Malcolm In The Middle, Lois, tired of her three boys constantly arguing, imagines them as girls instead, in a world where everything's better and they give her unconditional love. But she realizes by the end of the episode that girls would be bad in different ways — bitchy and keeping all their secrets from her — and that her boys love her in their own genuine way. (The episode is also funny to watch to see Hal in a fatsuit and Francis, the eldest son, as a girl — unlike the other three, Christopher Masterson actually played the female version of himself.)
At the end of the pilot episode, after Wyatt (the cautious one) tells Lisa (hot computer-created genie) that he's happy and she disappears, Gary (slacker) is ticked and states he'd only be happy if Wyatt was a killer babe. At that point, Wyatt is turned into a hot blonde.
Later in the series, Gary is accidentally zapped into a phone sex worker.
In the episode "Feminine Mistake," Wyatt and Gary want to understand women better, but aren't satisfied with Lisa's help. So, of course, Lisa makes them look like girls. "Wynona" and "Garyette" get hit on by everyone including Wyatt's brother Chett. Played for laughs as Wyatt and Gary see themselves as girls only in mirrors and the audience sees them as girls when they flirt with their minor friends (or have a hissy fit.) But when boys try to pick them up....
The Gumbies on Monty Python's Flying Circus briefly turn into girl-Gumbies at the end of "The Buzz Aldrin Show" for no particular reason. Their only reaction upon turning back is "OOH! THAT WAS FUN!"
In the third season of MisfitsCurtis gains the ability to change genders.
This is the main plot device of the Korean drama series Secret Garden, in which it turns out that the female lead's dead father engineered a body swap between her and her soulmate, as a part of an elaborate plan to heal her from grief caused by his death, which was caused saving the soulmate's life. The three switch three times over the 20 episodes, each iteration powerfully shifting the complex dynamics between them and with those around them.
In the first episode of the Argentinian show Lalola, a stereotypical male womanizer is transformed into a woman. The series explores his subsequent misadventures. The show has become an international success, with reboots in at least 6 different languages.
In the drama Wizards Of Waverly Place, Max undergoes one in "Three Maxes and a Little Lady", thanks to a mutant spell cast by Alex and Justin. The end of the episode states that he will remain female for a while.
The prophet Tiresias was transformed into a woman by Hera as punishment for killing a mating female snake. Seven years later, he killed a male snake in the same location and was changed back into a man. In some versions of the story, he continued to change sex every seven years afterwards for the rest of his life. As a result of his unusual experience, Tiresias was later called upon to settle an argument between Zeus and Hera over which gender enjoyed sex more (as he alone had experienced it from both perspectives). Tiresias said that women enjoyed it more. Hera's response to that is why he became known as "the blind prophet".
The goddess Artemis turned the Cretan hunter Sipriotes into a woman for staring at her naked body while she was bathing.
In his Metamorphoses Ovid wrote of Iphis, a daughter of Telethusa and Ligdus, who Ligdus had said — when Telethusa was pregnant — he would kill if born a girl. The goddess Isis told Telethusa to bring Iphis up as a boy, and Iphis eventually fell in love with a woman — Ianthe. So Isis turned Iphis into a man. They lived Happily Ever After.
In the Mahabharata, Shikandin, the reincarnation of Amba, was born specifically in order to kill Bhishma. He was born as a girl but was brought up as a boy due to Prophecy Twist. He exchanged his female body with a Yaksha and was turned into a man.
The God Vishnu turned temporarily into a beautiful woman called Mohini in order to seduce the demons away from eating nectarine that would lead to immortality. He coyly teased them about it, transformed back to his original self and gave the pot to the gods.
The gods hired a contractor to build their heavenly city. They let him name his price after he did the work, he asked for the goddess of love's hand in marriage. He was a giant, with a giant horse, so they had to distract the horse and get him outa town. How'd they distract the horse? Why, by having the trickster god Loki, noted male, transform into a hot mare, of course! Loki actually got pregnant from this and bore the eight-legged horse, Sleipnir, who Odin nicked to be his warhorse. Loki didn't mind, presumably wanting to drown the memories in mead as quickly as possible and never see a reminder again. Another version of the myth has the Giant getting Odin's wife if the work is completed by a certain date, and Loki distracts the Giant's horse as above to delay the work past the due date so she doesn't have to pay up.
In the myth where Loki invades the gods' banqueting hall to insult them all, he and Odin both charge the other with having turned into a woman — a real woman, who had borne a child and nursed it.
According to Herodotus' Histories some Scythian raiders once made the mistake of sacking a temple of Venus Castina (the aspect of Venus who looks after the souls of women locked in male bodies.) The Goddess responded by turning the raiders into women.
Happens in a rare myth of Guanyin, the Chinese interpretation of Bodhisattva Avalokiteshvara, who is recognized as almost exclusively female due to a mixture with his/her own Tara and some fertility goddesses (although Avalokiteshvara truly appears only in 4 of his 32 incarnations as female). It is connected with a school of Shaolin, there, Guanyin changes into a man for the sake of the group and later is "allowed" to stay that way.
The "Girdle of Femininity/Masculinity" is a magic item dating back to AD&D. It changes the wearer's sex.
The Changeling race from Eberron can change appearance at will, this includes gender.
Most shapechanging magic (such as Alter Self) allows the caster to choose the gender of the assumed form, along with more typical alterations such as height and build.
Many "random" magic effects in D&D include involuntary sex change as one possible result. Wild Mages in particular tend to suffer from it.
The infamous Tomb of Horrors has this as a result of one of the many, many traps, with the added bonus of alignment reversal.
In the third-party supplement The Book of Erotic Fantasy, there is a sex-change spell with the memorable flavor text "I'm a girl! I'm a girl! I'm a... no, wait, let me check."
Forgotten Realms has a special spell for this, that was repeatedly used in the Elminster Saga novels, though didn't make it into sourcebooks. Eilistraee allowed this as an option for her rare male priests (being a female is the only way to understand her divine dance). Mystra at least sometimes did this too, though her high-ranked servants are likely to shapeshift into lots of forms either way while going about their usual business.
Greyhawk got Zagig's Gender Shift spell introduced in Dragon #270. 3rd level, but unlike Alter Self it remains until dispelled or negated.
Mekton Zeta cites this as a sample use of the "Special Effect Weapon" Stupid Mekton Trick.
In GURPS, "Hermaphromorph" is a cheap (5 point) Advantage that allows a character to change sex at will.
Similarly, Eclipse Phase has the "Sex switch" augmentation that allows one to change sex at will, but the transformation takes a week. For some reason it only takes a day in a healing vat to permanently switch sexes.
The Lunar Exalted have access to a charm which allows them to change sex at will. Their God/Patron Luna enjoys the same power and has no set gender. If that wasn't weird enough, Luna is the lover of Gaia, who is very female. Make of this what you will. Luna sometimes appears in the form of a Pregnant Boy.
Alchemical Exalted have a charm that allows them to shift their physical appearance, allowing them to be males, females, and even hermaphrodites or sexless. Since they are sterile in any case, the changes are purely cosmetic, though.
With Sidereal Martial Arts, it's possible to make someone switch genders by punching them.
Scion has an Epic Appearance perk mentioned in the God rulebook, that allows the Scion to change everything about his/her body, including gender, and becoming a hermaphrodite. They're even fully fertile.
Unknown Armies provides players with at least three permanent ways to magically change their character's sex, a few more temporary methods, and several canonical one-off accidents. In addition, since the game is set in the Present Day, gender-reassignment surgery is also available - and explicitly necessary for correcting some magical accidents.
In Warhammer 40000, the Chaos God Slaanesh typically uses the pronoun 'He'. However, he in fact is neither male nor female yet both at the same time. He assumes whatever form the person viewing him would find most attractive, which means that he can either be a fully functioning male, female, hermaphrodite or whatever else a person finds attractive at any given time. His traditional form is a weird sort of hermaphrodite, being split down the middle vertically as a woman on the right side of the body and a man on the left. The same goes for his/her breeds of daemon, including the more animalistic ones.
Cthulhutech has a First Order (low level) spell of the Transmogrification style called "Beckon the Unexpressed". Its other names are Aphrodite's Touch and Gender Bender, which sums it up fairly well. By magically "tweaking" the target on a chromosomal level, the target switches gender in a painless fashion over a period of three days. The ritual is legal (though it requires a permit), and implicitly a person "switched" in this manner is fully functional in their new role — the spell has replaced surgery for gender reassignment. Because the ritual only requires an effigy of the target and not the target's actual presence, it's noted that immature occultists like to use it for pranks. Especially in college. As well as merely switching men to women and vice versa (the change is permanent, but easily undone with a second spell), casters with sufficient occultic skill and knowledge of physical medicine can use this spell to create different varieties of fully functional gender ambiguities (people with the body of one sex and the reproductive organs of the other, or a "true" hermaphrodite with the body of one sex and the organs of both).
The Mage The AwakeningLegacy known as the Daksha become Hermaphrodites after a certain degree of initiation, but also have the ability to shift between a male and female form as they see fit (although they will generally consider the hermaphrodite form their true one). They do this because they believe it is the mark of their superiority.
Demitri Maximoff (or Maximov; it changes) has a move called Midnight Bliss, in which he turns an opponent into a woman before sucking the life out of her. (What happens when he uses it on female opponents varies wildly between victims.)
In regards to this, in SNK vs Capcom Chaos, Goenitz is one of the playable characters. His Midnight Bliss form (called Goeniko) has become very popular as a result, ironically turning every gamer's worst nightmare into every hentai artist's dream.
Zohar, The Rival in Silhouette Mirage, has two forms with opposite attributes and gender. As Zohar Metatron, he's a Silhouette-attribute who wields a sword; as Zohar Sandalphon, she's a Mirage-attribute with a gun.
Edwin is transformed into a woman by a Netheril practical joke in Shadows of Amn (he believed it would transform him into a lich), and is unable to turn back. The game even gives him a second soundset for his female form (though it does nothing to his portrait). He is eventually turned back after many trials, tribulations and being snarked at by most of the other party members. However, by keeping Edwin in your party through Throne of Bhaal, his "Where Are They Now?" Epilogue reveals that he later tried to make his name by challenging Elminster to a magic duel, who had apparently heard of his previous mishap and made sure to apply the effect permanently this time....
Being based on D&D, the Wild Mage class has it as one of the random effects.
There's also a girdle from the first game that has no effect but to instantly and permanently change the gender of whomever puts it on.
Nights Into Dreams has a rather interesting example. NiGHTS, the character of the games gender depends on what gender the person viewing NiGHTS sees NiGHTS as. Since NiGHTS combines with people to escape the Ideya Palace, you've got to wonder what happens when someone sees him as the opposite gender...
Disgaea allows you to transmigrate any non-story character into another class, with the option of changing gender in the process. If that's not enough, you can choose to turn him into a penguin instead.
A stranger example comes from the Disgaealight novels. Lamington states that angels have no set gender to begin with, instead taking in traits from the environment and their own emotions having an effect. Apparently their choices in weaponry also affect the outcome as well, which gets weird when you figure that the angels in-game are all female.
Another Nippon Ichi example comes from Soul Nomad And The World Eaters. The player character, Revya, was explicitly born as Median's firstborn son all of about 200-some years back. This trope comes into play if you choose to play as a female. And considering the Disgaea 3 DLC has Female Revya...
Neo Mr. Do has a powerup that turns the title character into a woman, as if Mr. Do wasn't creepy enough...
In Persona 4, Shadow Naoto tries to turn its creator into an adult male through body alteration. Luckily, you can stop it before that happens because all shadows you haven't personally stopped have murdered their originals, the implication being that the operation would have Gone Horribly Wrong.
The Temple of Shadows has the "Wheel of Misfortune", which kills human sacrifices through random means. Among its possibilities are electrocution, impalement, beheading and "Gender Change."
The player has a chance to use a sex changing potion after buying Castle Fairfax. This potion is one-time use and irreversible (the game saves immediately after you use it), unless you play Co-Op online and use someone else's potion. The change is generally acknowledged by the NPCs, but your spouse couldn't care less (unless the situation becomes incompatible and your child readily starts calling you 'mum' or 'dad'.
After the introduction of the Super Science power pack in City of Heroes, it was possible to use different body types (and, therefore, change your gender when you change your costume) across different costume slots.
Specific to Pokémon Crystal, if the player chooses the female avatar, they appear as the male avatar if they want to trade with any other game, as the sprite data for the female avatar doesn't exist in any other compatible version. However, in this game the player's gender choice was purely aesthetic, so nothing is made of it.
Azurill has a 1 male to 3 female gender ratio, while its evolution Marill has an even gender ratio, meaning 1/3 of female Azurill become male upon evolution. In other words, it grows a dick. (This is most likely unintended.)
Chronormu, a bronze dragon who 1) had a name consistent with the naming standards of male bronze dragons, and 2) prefers to take the humanoid form of a female gnome named Chromie. This appears to have been an error, though, as her rare appearances in dragon form have since been changed to either just say Chromie, or Chronormi (the female suffix for bronze dragons).
Player characters gained access to character appearance resets for $25 in 2008. This includes the ability to change your character's gender. This was used as an explicit selling point for the resets.
In "Wrath of the Lich King", the player is led through quests to a village entirely inhabited by Hyldnir, female Giants. For purposes of disguise it the player must transform into a Hyldnir, regardless of original gender.
Using an Illusion Potion near a character of the opposite sex.
Certain items that transform you into traditionally male creatures do (or did) cause you to be considered male as far as gender specific titles are concerned, such as the Iron Boot Flask which turns you into a male Iron Dwarf. Strangely, while the Pygmy gnome transformation of Pygmy Oil turned the player into a female Pygmy gnome, it would also result in female characters' titles changing to the male equivalent.
Actually a play mechanic in Cave's Bullet Hell series Video Game/Espgaluda — entering "awakening" mode causes your character's gender to flip, and for all the bullets to move in slow motion. It also makes it possible to cancel opposition bullets by killing the shooter to rack up huge scores. However, if the meter showing how long you can remain gender flipped runs out, you're immediately shunted back to your original gender, with bullets moving at double speed.
The Makeover Mage in Falador will change your gender for a fee of 3,000 coins.
There is a members quest where one of the tasks requires you do do this if you are male, as, in the words of the enemy in question, "No mancan kill me!"
In Jade Empire you can encounter the Furnace of the Mad Science God Lord Lao. There are various recipes of combinations of working parts and fuel that can upgrade your character, and experimenting with other mixtures will usually just summon demons or light you on fire. However, there is one unmentioned combination that will briefly swap your character into the opposite gender (Complete with matching clothes!). This is temporary however and you shift back five seconds later.
In Geist, John Raimi, the ghost of a man, has to possess several women to progress through the game. This actually becomes important gameplay-wise when you possess towel-clothed Anna, who will not walk past a male-guard without proper clothes.
Gaia Online lets you change your avatar's gender three times for free, then begins charging on the fourth. A "Gender Bender" potion was also made available.
Civilization II, like most games in the series, has a "unit upgrade" mechanic - the "Leonardo's Workshop" wonder, in this case. When built, this wonder will turn all your Diplomat units into the more advanced Spy. The Diplomat is depicted as a stereotypical old-fashioned diplomat, a little man wearing tails, a top hat, and grey striped trousers. The Spy, however, is a busty female wearing a Little Black Dress. So your diplomatic corps not only gets better skills, but free sex changes!
The Amulet of Change from Net Hack switches the player, then disintegrates, leaving him/her stuck. Since this has next to no consequences on gameplay (foocubi will seduce the opposite sex and attack the same, only females can lay eggs, and strange monsters' hatched eggs sometimes ignore male characters), the amulet is considered Vendor Trash except for stunts like making male Valkyries, and a possibility that it's what an unidentified amulet is isn't considered a good reason not to try it on.
Can be done in Kingdom Of Loathing at a very dodgy street doctor's clinic in the sleazy back alley.
Although not necessarily a true case of Gender Bending, the 1996 game Pandemonium by Crystal Dynamics has a cheat labeled; BODYSWAP, which, when inputted shows the statement "Gender Bender!" The cheat itself, however, only enables in-level character swapping between Nikki and Fargus.
In the MUGEN-based game The Black Heart, Animus constantly switches between male and female appearance. Many attacks are "gender-specific", but he automatically changes gender as appropriate when they are performed, so the changes are mostly cosmetic.
In Fallout 3, as you leave Vault 101 after the tutorial, you have the option of reassigning your character's gender. In the PC version, you can also do this with console commands.
Though this has yet to show up in any game, in the lore of The Elder Scrolls, the Argonians are apparently sequential hermaphrodites, and they change gender entirely at certain points, these are known among the Argonians as "life-phases".
In Homestar Runner, Strong Bad explains what he would do if he ruled Free Country USA. Things start out plausible, like the King of Town being stuck in a box of peas, Coach Z getting a new jacket, and Homestar leaving, and then they get weirder (such as Pom Pom looking like an ABA basketball and Strong Sad being the devil). The weirdest of all? He plans to turn Homsar into a "modestly hot" girl. After realizing that this is Homsar he's talking about, Strong Bad proceeds to decide that his imagination is broken.
El Goonish Shive is notable for the sheer number of gender-bending gags and storylines. A Transformation Ray in the Chivalrous Pervert's hands, a character able to transform others without such a device, a Half-Human Hybridshapeshifter who can change forms, including both male and female at will, though seldom has an actual reason to do specifically this, and finally Elliot ends up with a suspiciously-specific shapeshifting ability but tries not to use it. So, of course, the phlebotinum behind Elliot's hijinks builds up, and either he uses it several times a day to keep it controllable or it activates spontaneously anyway. The author is on record about how much fun it is to torment Elliot. All of the major characters have their gender swapped at least once. As a birthday party theme.EGS also gives us this wonderful line when Sarah and Susan are arguing over whether it's healthy or not when Elliot "fails at perversion":
Similarly, The Wotch is pretty much based around the trope; whole groups of male students at Tandy Gardens HS (note the initials) have been permanently transformed into females (four of whom would later be featured in a Spin-Off series, Cheer!), and some of the other male characters seem to have become addicted to being temporarily in female form. (The authors of both comics readily admit to being a little too interested in Shapeshifting. Their readership is in the tens of thousands. We blame 1980s cartoons.) In one particularly strange example, the Wotch herself has an older brother who likes to relax by taking on the form and personality of a four-year-old girl.
In The Order of the Stick, Roy has to don the mystical "Belt of Femininity/Masculinity" to escape a pair of would-be assassins. This is an actual magical item in Dungeons & Dragons, though this one reacts to Remove Curse better. Breaking the trend slightly, Roy is NOT a beautiful woman, and is still bald. Also a common theme is the fics written in the Crack Pairing thread on the forum. And a theme week for avatars every year.
A storyline near the end of It's Walky switches the genders of Walky, Joyce, Head Alien, Monkey Master, and the aliens' computer due to Unpredictable Results. Entropy nearly kept them that way, but The Wanderer intervened. The trope is played with somewhat as well. Joyce points out to Walky that despite having changed genders, they're still straight, leading to humorous moments between them and their team mates. It's later revealed that male-Joyce's "equipment" was bigger than Walky's regular package. Walky is not happy to know this, to say the least.
In Gender Swapped, the main characters are hit by a ray gun that changes their sex and rewrites their lives while they sleep. The machine, known only as the 'GSM' has been built by scientists for a yet to be announced reason. Two of the three main characters were hit by a split beam setting the plot in motion, the third character Elise, whose name is now Elyps, due to an odd set of circumstances, has to live as a boy without the luxury of the people closest to her thinking she was always that way. This comic has followed both the First and Second Laws of Gender Bending.
Done briefly in The Last Days Of Foxhound, in which Decoy Octopus (who, through drinking their blood, can take on another person's appearance) disguises himself as Sniper Wolf. It's a very complete transformation.
In Narbonic, Mad Scientist Helen Narbon invents an instant gender-change formula. She gleefully uses it in several storylines, not least to make her sex life more interesting. When Dave and Helen briefly separate near the end of the comic, his reaction is "Good lord, I'll never have lesbian sex again!"
The Insecticomics has several instances of characters spontaneously changing their gender, although being that they are mostly androgynous Transformers gender isn't much of an issue for them.
In a later strip, the resident Moral Guardian Lady Jaye protested that the male Thrust was pursuing a relationship with Dreadmoon (also male), whereupon Thrust promptly declared himself female and went off to hit on Dreadmoon again. Since the characters and the author both refer to Thrust as "she" from this point on, apparently Thrust never bothered to change back.
Exiern is about a mighty barbarian who went to save the Damsel in Distress princess from the evil wizard. Accidentally nullifying his own ability to cast dark magic, the wizard resorts to pouring all the power he can into a light magic spell, transforming the barbarian into a beautiful woman.
She !s me (Oh no! I'm a girl!) The story of a guy who one day wakes up as a gal. Don't think of this as a funny bodyswitch comedy, but as a serious evaluation about the question "What would you really do if...?"
Axe Cop has two prominent examples of this trope, both revealed in "Ask Axe Cop" installments:
In a What If? scenario, Axe Cop revealed that he'd only want to have kids "in a jillion years when I am done with my job" (i.e., the last bad guy in the world has been killed.) Axe Cop would then use unicorn magic to turn his best friend Sockarang into a girl, and they'd have a family together.
In another (canonical!) example, Axe Cop teamed up with Abraham Lincoln, who turned into Abraham Lincoln: Explosion God and "put a bomb inside every bad guy." With all the bad guys in the world destroyed, Axe Cop used his magic unicorn horn and wished for Abraham Lincoln to be a girl. They got married, and lived Happily Ever After... until Axe Cop got bored. Presumably, the bad guys were resurrected and Axe Cop went back to doing his job, but the final fate of Girl Abraham Lincoln is, as yet, unrevealed.
This is the main power of the Tiresias Orb (see the "Mythology" section) from Eerie Cuties, which Blair steals, uses irresponsibly, and accidentally breaks, leaving Ace stuck long-term; much, much later, kissing Kade after touching Blair causes Ace to transfer the curse to him for a while, until Chloe figures how how to use this effect to break the curse completely.
Magic And Physics has Shelly, who, oddly for this trope, doesn't seem to remember being a guy ever. However, her brother does, and seemingly the Author and the Writer do too.
In Jix, one of Remula's personalities, Lamerix creates a device that does this. She tests it out on Lauren, changing her into a guy. Lauren gets mad about being temporarily stuck and uses it on Lamerix, but with no noticeable change (due to no major sexual dimorphism in Ambis and the fact that fur covers their private parts). Lauren convinces Lamerix to temporarily change her husband Paul while she's trying to figure out how to reverse the change.
In Quantum Vibe, Nicole meets a female Sexbot named Hitomi who starts coming onto her. When Nicole wants to back out ("I really don't, y'know, flop that way"), Hitomi simply swaps gender to suit Nicole's inclinations. This simply leaves Nicole aghast.
In Dragon Ball Multiverse, Syd from Universe 6 can switch genders with others upon eye contact. She tries this on U13's Prince Vegeta to even out their power differences, only to find out that Vegeta is still Vegeta, woman or not.
In Girl In My Dream, Ji-Hoon gradually becomes a female named Ji-Hyun as he dreams.
The Whiteboard: After pressing a button with a Shmuck Bait warning sign, in the May 22, 2012 strip, Roger is transformed into a woman.
In Somewhere Different, protagonist Mark is hit by a truck, and saved from dying by being turned into a girl.
In Sparkling Generation Valkyrie Yuuki, the title character starts out as a teenage boy, until he watches a "Magical Girl" DVD and Hermod, in the form of a monkey (or marmoset), comes out of his TV and turns him into a valkyrie, a female warrior of Norse mythology. This almost immediately leads to a Man, I Feel Like a Woman page.
One Girl Guy Army: The Main character Tait transforms into a blue haired girl with a blue ribbon wrapped around his neck. The other main character Icarus also revealed to have been turned into a girl in the past Icarus is revealed to be the Amazon princess Amelia who had his male essence forcibly taken out magically by the Amazon Queen who placed her own female essence in place of his own.
In Sinfest, the "Trans State" is a section of the woods that instantly changes a character's sex.
In Mischief in Maytia, one of the characters gets crushed by a flying saucer and is given a rental body while his real body gets repaired. The rental body is that of a teenage girl.
Parodied in Murry Purry Fresh And Furry when Melvin decides to reboot his webcomic Fart Police to be a gender-swapping high school comedy.
At Arms Length got one when they introduced the first place winner of their character contest. A human from a parellel world appeared in front of Reece and Sheila, and the two used a disguise spell to make him appear as something from their world, only for something unexpected to happen, resulting in the human's gender to be switched in the process.
Several of the main characters are gender bent by an "Exemplar" mutant power, which involves involuntary shapeshifting to a "BIT" (Body Image Template). A BIT is that person's mental image of a perfect body, which is occasionally the "wrong" gender — although Exemplar mutations tend to have a side effect of a certain level of acceptance. It should be noted that the First Law is in full effect in the Whateley 'verse — as a rule, it is not possible to undo or really change an Exemplar mutation.
Other than the Exemplar mutants, one main character is changed to a girl by being bonded with a powerful female elf spirit, another due to a poorly worded prank by her little brother, another by a magic sword, and yet another hasn't changed at all but is actually a Transsexual trying to find a way to become a real girl. Oh, and then there's Hank, who's gender bending the other way.
In Take A Lemon (seen here), Marshall Steen wakes up one day as Marsha. S/he determines that it was caused by a scientific experiment gone awry and then decides not to change back for a few months, just to prove that s/he can cope with the situation. It turns out she wasn't actually transformed, she'd just been give the memories of her male counterpart from an alternate dimension.
The plot of Transplanted Life. In fact, in that story, the only way a mind-transfer works is between genders.
Most of the characters in The Trading Post, one of whose writers is also behind Transplanted Life.
The Satyri series (and possible future webcomic) by deviantART artist DP Ragan is about a series of virgin males who are cursed by a group of succubi, either by being pulled into hell and having their soul infected with a fragment of a succubus' soul, or by using a cursed item (usually bodywash) that causes their skin to melt off, revealing their new, permanent form. The face is the last part to melt off — if the victim doesn't give in to the horrible uncontrollable itching as their skin bubbles and melts at the edges the face will regenerate their human body over a few weeks of constant torture; the gender bending, however, is permanent. If they don't manage to keep their hands away (and it's not common knowledge to do so, most people don't last more than a few seconds), or if they managed to get pulled into hell for the personal treatment by another succubus, they are now permanently stuck as a Satyri — a vaguely Satyr-like half-Succubus. Satyri traits include a tail, horns, elflike ears, Ungulate hooves (think "Draenei"), inhuman (yellow iris on black) eyes, unnaturally colored latex skin and hair (red, blue, and "bubblegum" being the most common), and an enforced lack of nudity taboo. Wings are also common, especially with Satyri who have completely "went native" and turned into outright Succubi.
deviantART in general has entire communities surrounding this trope. Just put "TG" into the search engine and enjoy.
In the Paradise setting, human beings are randomly, permanently changed into Funny Animals (though the change is Invisible to Normals). A small percentage of Changed also change their gender. Given the Wish Fulfillment nature of the setting, the number of gender-Changed who appear within stories is somewhat disproportional to the amount that exist setting-wide.
Okashina Futari is a story of two siblings, a boy named Ayumi and a girl named Satori, who have the ability to change each other's gender (which cannot be done onto themselves) merely by wishing it. As expected in most gender-bending, the boy-to-girl transformation is more frequent. They can also change the other's clothing, including undergarments, but they can't change the gender and not change the clothing, nor can they change the clothing into garments worn by the other's gender (e.g. Ayumi as a girl wearing a man's suit).
In Chakona Space skunktaurs, which were a competing project to the chakats' development, can switch between male and female. They're born male then change to female for the first time at puberty and can trigger the change at will from then on.
Lea Wilderson appears to be the blog of a man named Lee Wilderson who turns into a woman.
SCP-113, a piece of jasper that turns anything with sex chromosomes that touches it into the opposite gender. Although, the change is rather painful, there is a 25% chance of the subjects genitals being obliterated and multiple exposures may cause [DATA EXPUNGED].
The Foundation also has a character named Agent Diogenes, who has been exposed to it so much that they either now have no gender, or are both genders. In either case, they can't remember which gender they originally were.
The Body Surfing Dr. Bright has inhabited a number of female hosts.
Lloyd In Space hangs an entire episode on a one-shot who's "Neither Boy or Girl" and of a species that chooses its own gender at the age of thirteen.
In one episode of Johnny Bravo, "Witch-ay Woman", a fortune teller tries to teach Johnny a lesson in showing women respect by turning him into one.
In an episode of Ozzy And Drix, when Ozzy accidentally ends up in the body of a girl instead of his usual (for the TV show) human host Hector, Ozzy's own sex starts changing. He very nearly becomes completely female, but never loses his beard.
"Operation: F.U.T.U.R.E." has a young misandric lass who gets a "Girlifyier" gun from her alternate future self. Numbuh Four gets his hand zapped, and in the dystopian alternate future is the only adult male left. He becomes the leader of the Boys Next Door and with the help of Numbuh Three's granddaughter develops an "Boyifyier", and a sex-swapping battle ensues. He manages to evade this future by going back in time and changing things.
In "Operation: C.A.R.A.M.E.L." where Numbuh Five's candy-hunting rival, Heinrich von Marzipan, turns out to have once been a girl, who was turned into a boy through some magic caramels. And, through some very weird logic, this is the reason he has such a big grudge against Abby.
In "The Boy Who Would Be Queen," Timmy, Cosmo and Wanda all change sexes. (Wanda is not a very attractive as a man.)
In "The Good Old Days!" Timmy wishes himself, his grandfather, Cosmo and Wanda into a 1930s style cartoon where Wouldn't Hit a Girl is a law of the universe. He therefore makes an additional wish that the Vicky analogue was a boy so he can defeat "him".
It's never been revealed how Timmy's parents, who dressed as each other for the Halloween Episode, were affected by Timmy's "Real and Scary" wish. Apparently, it wasn't traumatic for them, as they dressed as each other again in "Take and Fake".
In one episode, an invention turns Johnny into a hot girl for about 5 seconds, then overloads and turns him into a hulking female monster. She turns back to normal a few seconds later.
In a later episode, an invention turns Susan and Mary purple, then huge headed, then male. They revert after a while, but it was All Just a Dream anyway.
Another episode has Johnny and Dukey turn into female rollerbladers to win a roller derby.
The last episode of Adventures Of Sonic The Hedgehog has Sonic and Tails transported into various fairy tales. In the first one they visit, they're Hansel and Nettle (Gretel). Sonic is Hansel... and Tails is Nettle. Disturbingly, four-year-old Tails gets boobs as a girl. He even lifts up his dress to verify it: "I'm a girl!"
Bender from Futurama blurs the line between the "already ill-defined robot sexes" more than once:
In "Raging Bender", he becomes a fighter for the Ultimate Robot Fighting league, and is first billed as "Bender The Offender"; as his popularity falls, however, he's forced to play the Gorgeous GeorgeHeel role of "The Gender Bender", dressed in a blonde wig and pink tutu.
In "Bend Her", Bender poses as a fembot to compete in the Olympic games, wins several gold medals, and then has to have a sex change in order to pass the gender verification test. As the fembot "Coilette," Bender begins a relationship with the robot actor Calculon — planning initially to marry and divorce him so she can take half his stuff. However, it turns out that Calculon is genuinely in love with Coilette, and prepared to give up acting to be with her. Bender and the gang end up concocting an elaborate scheme to fake Coilette's death at her wedding so that Bender can undo the sex change without hurting Calculon.
"Neutopia" brings the entire Planet Express crew to a planet where gender is unknown, and an alien swaps their sexes. Leela and Amy do not enjoy being male, while Fry, Bender, and the other men-turned-women find the experience fun. And in a Call Back, Bender's female form is Coilette.
In "Prisoner of Benda", Amy and Professor Farnsworth use an Applied Phlebotinum device to voluntarily switch bodies (she wants to binge eat without consequences, he wants to be young again). Once they try to switch back, however, they discover that the machine cannot be used on the same two people twice...leading to a barrage of body swapping hilarity that includes (but isn't limited to) Bender inhabiting Amy, Leela switching into the Professor's body, and Amy switching with Hermes.
In the Batman Beyond episode "Out of the Past", it turns out Ra's Al Ghul has taken over his daughter's body, which is even more disturbing than it sounds. Ra's can speak with his Ra's voice, even though he has the body of a woman... the transition is outright creepy. Furthermore, Ra's still acts in a very effeminate manner, despite the voice. Remarking on the situation:
Terry: Lady, that is the sickest thing I've ever seen. You're creeping me out! Bruce: You? She kissed me.
In Thundercats the evil Mumm-Ra has transformed into a female on at least four separate occasions:
In "The Garden of Delights", Mumm-Ra assumes the form of a faerie queen to lure Tygra into a trap.
In "The Mask of the Gorgon", he turns into Nada of the Warrior Maidens.
In "The Queen of Eight Legs", Mumm-Ra turns into a tiny female fairy called Diamondfly.
In "The Astral Prison", Mumm-Ra transforms into the Nether Witch, which is implied to be an alternate identity he regularly assumes.
Spider Man And His Amazing Friends: In "Seven Little Superheroes," the Chameleon, a male villain, displays his shapeshifting powers by assuming the forms of female heroes Shanna The Jungle Queen and Firestar (as well as several male characters.)
Hogatha in The Smurfs switches genders when she becomes a Smurf in "The Fake Smurf".
In Wakfu, season 2, episode 10, Evangelyne and Amalia temporarily turn male thanks to a magic potion to be able to play Gowbbowl.
The opening to an episode of Arthur had Arthur wondering how life would be easier if people had various special abilities, including being able to turn into other people should the need arise. The Imagine Spot shows Arthur about to be caught by his mother for making D.W. mad, so he transforms into his grandmother and confuses his mom.
Kim Possible and Ron Stoppable once swapped bodies. However, the only time the fact they don't have the same gender affected the episode was when Kim forgot which bathroom at school "Ron" was supposed to get in.
It's never been stated how far Camille Leon can go while shapeshifting into males.
Towards the end of The SimpsonsTreehouse of Horror episode, "Stop the World, I Wanna Goof Off", while Lisa was messing with a reality changing watch; Homer, Bart, Marge and Maggie are briefly gender bent.
In the My Little Pony: Friendship Is Magic episode "Magic Duel". Twilight Sparkle briefly changes Applejack from a mare to a stallion. It turns out her entire magic display is fake and it was really Applejack's brother Big MacIntosh pretending to be a gender bent version of her.
On Samurai Jack, one episode saw a character assume the form of the opposite gender to trick Jack. Aku assumes the form of female warrior Ikra, to trick Jack into leading him to a way back to the past, so as to destroy it.
5-alpha-reductase deficiency (5-ARD), known crudely as "Guevedoche" ("Balls at twelve") in the Dominican Republic and simply "Kwolu-aatmwol" ("female thing transforming into a male thing") in Papua New Guinea, in which a genetic male is born with what appears to be female genitalia under casual scrutiny, only to "turn" male when they hit puberty. This is a rare but inheritable genetic disorder, seldom seen outside the above-mentioned places. Allegedly, because it is comparatively common in small, highly insular communities, most of those affected adjust with surprising ease.
Meet Wolbachia, a bacteria that primarily affects arthropods (insects, arachnids, and other bugs). It can, very rarely, turn infected males into completely fertile females. (More commonly, it turns them into infertile pseudo-females, and even more commonly it just kills them).
Some fish start out as male then change gender to female if the female dies. Others do the opposite.
There are also documented cases of peahens changing into peacocks.
Frogs and other amphibians are extremely susceptible to hormonal changes and can undergo severe physical changes that appear just weird for vetrebrates. One study shows that the popular herbicide atrazine can change male frogs to female.