Alright, the original series has Miharu Ratokie, rookie spy, sell out our heroes before falling in love with Kai. She dies while helping defend White Base, though.
Lalah has the misfortune of falling in love with the main protagonist AND antagonist. She dies taking a beam sword for Char, which proves a running theme in Gundam.
Zeta has Four Murasame and Rosamia Badam fall in love with Kamille, Reccoa falling in love with the villain, and Sarah falling in love with Katz AND the villain. Note, none of them actually switch sides but Reccoa. Everyone just mentioned dies, except Kamille, who ends up mind raped into almost catatonia and turned into The Ophelia until the end of ZZ. Unless you count The Movie.
Chane Laforet of the Lemures, in Baccano!. Of course, her comrades were planning to kill her in the end, and it could be argued that she remained true to the groups original purpose (protecting her father)...
Heck, she was three quarters of the way through turning before the show even started, and her whole team knew it.
Perona in One Piece was the only one of Gecko Moriah's minions who was female and fighting for him by her own free will. After some initial difficulties, Perona ended up helping Zoro, and post time skip she fought off Marines that were trying to catch the Straw Hats.
In Get Backers, a lot of the female villainesses are this.
Guren, one of the few major female filler antagonists in Naruto, does a High Heel Face Turn after coming to love Yukimaru, and cooperates with Naruto to ensure his safety. Unfortunately, she apparently dies protecting him. Or not.
So did Konan, the only female member of the Akatsuki, who admits that her morality and motivation completely depend on her childhood friend Nagato. So when he goes the route of Redemption Equals Death, she follows the new goals which he strove for, becoming the unofficial leader of their village.
Konan averts this, actually. It was Pein who was convinced to pull a Heel Face Turn, not her. Konan was only ever loyal to Pein, so she never actually switched sides.
However, then said organization has another female member take Eas' place. This time the trope is subverted, as this female stays evil to her demise, and the two males make Heel Face Turns.
Suite Pretty Cure ♪: Siren, the villains' second-in-command, exits the Heel Face Revolving Door in episode 22 and becomes Cure Beat. Unlike Setsuna, Siren used to be a good person and had spent a few episodes brainwashed, making her turn to heroism even more inevitable.
In the Utawarerumono anime, Touka of the Evenkuruga tribe is the only woman fighting on the side of Kucca Kecca, and the only one to later join the protagonist.
Renee in Innocent Venus when she rediscovers her feelings for an old flame.
Inverted in the original manga of the Hentai manga series Bondage Fairies, where the three villains are women, and their male slave is won over by and assists the heroine, Pfil. This gets him killed by Marcia, his master and the cruelest of the sisters.
In Kikaider during the four part OVA series, Bijinder decides to join up with the good guys after seeing how she actually cares about them.
Viro in Elemental Gelade has lived her entire life as a worthless Sting Raid, and is willing to do anything to become a real Edel Raid. She's sent undercover to spy on Coud, earn his trust, and if possible, separate him from his partner, Ren. Of course, Coud is the first person to treat her kindly, and she ends up falling in love. Unfortunately, Redemption Equals Death.
Subverted in Bleach, with Riruka. While she was the most reluctant member of her group and had somewhat of a crush on Ichigo, she ends up bonding more with Orihime than with Ichigo, and what made her realize that she truly was in the wrong were not her feelings for him, but realising that Ichigo was the only one truly capable of saving the X-Cution group, since their leader Ginjou was actually the Dark Messiah.
Juvia in Fairy Tail joins the protagonists' side immediately after her defeat. Though she was never actually a bad person, just gloomy and a bit anti-social, but she did belong to a villain group. (Gajeel from the same group, who is a guy, also does a Heel Face Turn, but that's later into the series, he doesn't join the protagonists entirely on his own accord, and he takes some time to get over his bad guy attitude and blend in completely).
Ultear and Meredy from Grimoire Heart are even more straight examples.
In the Green Lantern/Green Arrow teamup "Hard-Traveling Heroes II", Crackshot does this with barely a thought. Her boss is kind of weirding her out, Green Arrow's really hot, what's to consider?
Talia, daughter of Ra's Al Ghul, frequently betrayed her father out of her love for his enemy, Batman. In her case, it's more of a Heel Face Revolving Door, as she was always torn between her attraction to Batman and her loyalty to her father. During the "Death and the Maiden" arc, she turned against both men, having been betrayed by her father and sick of being used as a pawn by Batman to take Ra's down. By the time Grant Morrison started using her in his Batman Inc. storylines, she has become as evil as her father ever was.
In Batman 500, "All Mine Enemies", was the first mass team up by all the villains to kill Batman. They were instantly betrayed by Talia and Catwoman (the only two women in the room) who both joined the caped crusader and attempted not only to help him defeat everyone else but also to get his attention.
Diamondback (Rachel Leighton) was sent by the Serpent Society to help capture Captain America. Though she did not immediately abandon her mercenary ways, she fell in love with Cap and helped him escape. They later formed a romantic relationship.
In a feminist variation, Golden AgeWonder Woman stories often had her make extra effort to redeem female opponents, far more effort than she would extend to a male baddie. And she often succeeded. Even Paula Von Gunther, a Nazi and one of Diana's main archnemeses at the time, saw the light eventually.
Very few female X-Men villains stay villains. The Scarlet Witch, Rogue, Marrow, Emma Frost, Sage, Danger, Frenzy, and Callisto were all X-Men or X Factor villains who became good guys. Mystique and Lady Mastermind were also X-Men villains who became X-Men, although it didn't take (though Mystique is usually portrayed as redeemable and willing to do what she thinks is the right thing). The X-Men have had male villains change sides - Quicksilver turned hero when his twin sister the Scarlet Witch did, though she's always portrayed as the more heroic of the two (unless she's having mental problems, in which case it's portrayed as not her fault) - but not as many. And when you consider that they have more male villains but fewer male villains-turned-hero, you can see this trope in full effect.
Film - Animated
Mirage in The Incredibles; another example where the villain pushes her too far.
Lampshaded and subverted in Thunderball with SPECTRE's "Black Widow" Fiona Volpe, who warns Bond not to expect that from her. Bond, probably because he's a bed-hopping bastard, actually shrugs this off with "Well, you can't win them all". Volpe is actually the first Bond girl this doesn't work on, but it turned out he wasn't actually trying it on her in the first place.
Inverted in Live and Let Die where Bond sleeps with inept CIA agent Rosie Carver....then pulls a gun on her, revealing he knows she's actually The Mole for Big Bad Kananga. He threatens to kill her if she doesn't spill what she knows; when she says he wouldn't do that, they've just made love, he replies:
Zig-zagged in the fifth movie with Officer Neves. It seems like she'll end up in this role throughout most of the film, but both her and Hobbs end up joining forces with Toretto. She doesn't assist them in actually stealing the money, but does meet up with Dom again after the fact.
Happens with Galaxy agent Gila in the James Bond parody Our Man Flint.
Miss Teschmacher's betrayal was really Lex's own fault — he's so horrible to both of his henchpeople throughout the movie that the only reason Otis didn't betray him too was because he was too stupid to realize just how much Lex hated him.
The Baroness in the 2009 live action G.I. Joe: The Rise of Cobra, fighting her way free of the nanomites to help Duke. Stays good until the end, though the nanomites are still there, and could be subverted if her brother had a second control device to drag her back.
Averted in the Straight-to-DVD release Green Lantern First Flight, where, despite Boodika not being anywhere near as evil as the Big Bad Sinestro who she has allied herself with, she still ends up dying via impalement when Hal tricks her into shooting an energy rod to make it explode.
In the last of The Naked Gun films, Tanya Peters (Anna Nicole Smith) is the moll for a gang of terrorist assassins. After spending some time with the film's hero, Lieutenant Frank Drebin (who has gone undercover as an extra member of the gang), she apparently has a change of heart. She reveals where the gang leader has planted a bomb to Frank... but things go badly for her afterwards when Frank discovers she's transgender and reacts as though this is massively disgusting ("Unfortunate Implications" seems like much too generous a term for this scene).
In Disney's Condorman, KGB spy Natalia is a Defector From Commie Land, but she insists on doing so only to the titular "top secret agent", who is actually a bumbling comic book writer. Hilarity Ensues when he's forced to actually do all the spy stuff he dreams of in order to rescue her, but it's his naive charm that won Natalia's heart in the first place and helped prompt her defection.
Inverted in Spy Kids. The only female villain in the series (Teri Hatcher's character in the first movie) is one of the few to not be redeemed.
Trudy Chacon in Avatar is the only one of the soldiers who does a Heel Face Turn: the other characters who turn are either scientists or Jake Sully who (very literally) Go Native, but Trudy is simply one grunt amongst hundreds. While she does spend more time with the main cast getting Aesops and stuff, it certainly comes off as this.
Of course, it turns out that she was undercover for the FSB the whole time.
Nicci in the Sword of Truth series, though this is more about Richard changing her view on life than his sheer manliness, though that did help a little.
Denna is a less extreme example, as are the rest of the surviving Mord Sith.
Michael Stackpole of the X-Wing Series books and comics is good at subverting this. All of his villains are more or less equally evil, including Ysanne Isard, Leona Tavira, and The Mole, Erisi Dlart. Isard is the Big Bad, but she's not insane in the main series, just ruthless and calculating. Several people pull Heel Face Turns, but while there's a couple women among them they turn because Defeat Equals Friendship and because they were helped, like the men.
The Star Wars EU also had a minor case in the Witches of Dathomir, it's shown that the form of the dark side used by the witches leaves them disfigured. It overloads their bodies and causes blood vessels near the skin to burst, so any of the witches that are less disfigured, and prettier, would theoretically be easier to return from the dark side. This of course leads to Unfortunate Implications like Beauty Equals Goodness.
And let's not forget about Mara Jade, either (at least her falling for Luke seems to have happened a few years after her turn).
Happens rather frequently in Leslie Charteris' The Saint novels.
Played With In the Fablehaven series, Vanessa is one of the only villains to do a Heel Face Turn, but only out of necessity, and they distrust her repeatedly throughout the books. The Sphinx who was the Big Bad also turns good in the end, with the (Female) demon he controlled taking a position in a Big Bad Duumvirate.
Zig-Zagged with Diana from Gone. Throughout the series, she's probably the least outwardly loyal Coates kid, sometimes to the point of sabotaging their plans, but is the only one that actually cares about Caine. She stays even after Drake's and Jack'sHeel Face Turns but is still openly critical of how things are being done. Finally, in Plague, she leaves for good. But she remains on her own side the whole time, so there's no technical change, and she left more because Caine used her for sex and lied to her than an attack of conscience, although there's a little bit of that, too.
The writers of Star Trek: The Original Series seemed incapable of thinking women could be evil. Even villainesses tended to get the soft-focused-cheesy-musiced-hey-it's-a-hot-girl treatment. Women who did do bad things were typically portrayed as naive and/or misguided and therefore more deserving of pity than blame. Prime examples of this are Lt. Marla McGivers and Dr. Janice Lester. Due to Values Dissonance, modern-day viewers tend to take rather less kindly to these characters than was intended.
What about Sylvia in "Catspaw"? Not only is she an unmitigated villainess, she dies — along with her more sympathetic male partner. It probably helps that "her" undisguised form looked like it was made out of pipe cleaners.
Notably, the episode "Friday's Child" was originally scripted with Eleen handing her own newborn child over to the bad guys in an effort to save herself and then getting killed anyway as they only wanted the baby in the first place. Roddenberry vetoed this because he believed all women would be maternal. Note the writer of this episode was a woman, so apparently he thought he knew her own sex better than she did.
Let's not forget about Nadira, who was not only The Dragon (of sorts), but eventually her Heel Face Turn lead to a Love Redeems moment where the Big Bad himself surrendered himself to the good guys. Apparently her good behavior got her Parole after only 1 year of imprisonment.
Another example from Power Rangers: Astronema/Karone. This abides by both parts of the trope, being the first acting-Big Bad to have a Heel Face Turn and then getting cybernetically altered so she was RIDICULOUSLY evil so she could assume the role of true Big Bad... and then turning good in the end anyways.
Toxica from Power Rangers Wild Force qualifies. After being betrayed by both Mandilok and Master Org (resulting in her Disney Death) and having to be revived by Jindrax, she willingly helps the Rangers by telling them how to destroy the Nexus and rescuing Princess Shayla. She and Jindrax declare a truce with the Rangers afterwards and are last seen walking arm-in-arm into the sunset.
In Robin Hood the Sheriff sends a spy into Bonchurch in order to get information on Robin from the newly appointed Earl: Much. Tellingly called Eve, she ends up falling for Much and admitting everything.
This often (but not always) happens in the 1966 Batman.
Sometimes it would occur at the very end of an episode (just after the final commercial break) as a seeming sort of Aesop, as in "See, not all of these criminals are really bad people." This is exactly how the redemption of "Zelda the Great" came out (doubly notable since she was the villain of the show, not just a moll).
Maid Marilyn (the trashy blonde moll for the Robin Hood-themed villain Archer) switched over to the good guys.
Ultimately subverted (or is that averted?) in the "Minstrel's Shakedown" episode: The Minstrel's moll initially surrenders to Batman and Robin, but they admire her courage and seemingly let her go. However, it was all a ruse to bug the girl's purse so that the Dynamic Duo can listen in on Minstrel's plot. After she learns this, the girl turns evil again.
Veronica Palmer in Better Off Ted, described in one episode as being the only female in upper management at the evil organization Veridian Dynamics, uses her position in several episodes to subvert company plans, either directly or by manipulating one of her underlings. And, although clearly sociopathic if not a bit insane, Veronica is consistently depicted as the far lesser of the evils in the rare occasion that upper management is seen.
Ros Myers was in the inner circle of the Collingwood Cabal from the two-part premiere of Spooks series five, alongside her MI 6 boss Collingwood, her father Sir Jocelyn (the financier of the group's attempted coup d'etat), and newspaper mogul Paul Millington, who's been skewing his headlines to ensure maximum panic (and by extension, support for the "antiterrorism" measures upon which their planned police state will be built). She's quite appalled after Collingwood decides to pull the trigger on an assassination of the Home Minister and a staged airplane collision over London despite a presumed negotiation with Harry Pearce and his supporters, where he promised a short truce. Ros promptly texts Adam Carter to warn him of the assassination attempt, and spends the second part of the premiere passing intel of the Cabal's actions to Section D, before quitting Six and joining MI-5 at the end of the episode.
In Camus' L'État de siège (The State of Siege), Death (a female) betrays her master, Plague, to aid the male protagonist.
It can be difficult to actually characterize the rebels in that game as outright evil, especially the ones at the top of the ladder; all of them seem to be genuinely dedicated to their ideals, which her "turn" affirmed if nothing else, and given the depiction of the federation government in that game and particularly the head honcho the hunters answer to it's hard to condemn them.
Averted in the Dark Forces Saga; in Jedi Knight, the Dark Jedi who gets a Heel Face Turn is the teenage boy. The female Dark Jedi is The Dragon and is killed just before you face the Big Bad. Desann's apprentice Tavion is spared by Kyle in Jedi Outcast, but she just comes back even more pissed off as the new Big Bad in Jedi Academy.
Knights of the Old Republic: One scary male leader of the Sith academy. One treacherous but hot female underling. Guess which one you have a chance to turn towards the light?
Also with one rather hot Sith apprentice and her nasty-looking master with a massive chunk cut out of the front of his face. One of them you can save, the other always dies.
Neverwinter Nights: Identical to the above example, there's one hot female elf, one insane bald male human, and one ancient and really ugly lizardwoman. Guess which you can redeem?
The Shadows of Undrentide-Hordes of the Underdark campaign arc mostly averts this. No Heel Face Turns of any type occur in the entire series (unless you count the end of Aribeth's Heel Face Revolving Door and Nathyrra's backstory), despite having at least two female villains who might have made a good story to have redeemed them.
In the second of the Baten Kaitos series, Baelheit's little girl, Milly straight out defies him when the trio finally faces off against him in is floating empire. She pretty much confesses her love for Sagi in her sidequest just before this boss battle.
Indicators are that the City of Heroes update, Going Rogue, will have an example of this in demon-summoner Desdemona's background. She seems to be the likely contact for Villains seeking to turn Hero.
It actually had nothing to do with her finding Vyse attractive and her switching sides was actually caused because Galcian attempted to kill her along with the rest of Valua when he sent her back to the Empress and then promptly called down the Rains of Destruction.
Averted in Dragon Age: Origins by Ser Cauthien. She serves Loghain out of loyalty and honour, but questions several of his decisions. It's possible outside of the Landsmeet chamber for a Warden PC with high Coercion and Persuasion to talk her into walking away, but otherwise you're forced to kill her for her loyalty to a misguided tyrant. Seduction is not an option either way.
Morrigan is basically a walking subversion. A romance will cause her to soften considerably, but her plan to use the warden to create a MacGuffin Baby for her own (dubious?) purposes and leave the warden goes on as planned, regardless.
As it would seem, in BlazBlueNOL is setting themselves up to have a massive High Heel Face Turn in the end. First off, Litchi is genuinely good and probably just a victim of manipulation, not really loyal to NOL, some tinkering from other sources like either Carl or Bang could make her defect. Tsubaki is also pretty sympathetic; Jin, Noel and Hakumen would probably work on persuading her to get out of NOL rather than offing her. Then if the rumors about the identity of Phantom being the dead Nine coming Back from the Dead, Jubei would still want her back and other heroes could convince her. And the Puppet King Imperator Saya? It was Relius and Terumi that turned her evil in the first place, and Ragna wouldn't give her up so easily. Pretty much in NOL, those who are not redeemable lack a vagina (Hazama/Terumi and Relius)
Surprisingly, gender flipped in the second half of Fire Emblem: Seisen no Keifu. The brothers Johan and Johalva are both in love with Lakche (or her expy Radney, if you screwed up badly enough in part 1 to prevent Lakche from being born) and one of them can be persuaded to pull this by her and join the heroes. The other will go man scorned and she'll have to kill him.
And in the first generation there's Prince Jamuka, who has feelings for Adean the Priestess and she can convince him to join sides... and later he can marry either her or her twin sister Briggid.
Subverted in Blazing Sword. The bad guys consist of the Big Bad, two Anti-Villain brothers who only serve their organisation out of the loyalty they had before it was corrupted, a male assassin who kills Matthew's love interest, Leila, a Manipulative Bitch, said woman's loyal female underling, and a powerful female Morph who believes her only purpose is to serve the Big Bad. Who gets redemption? The male assassin. Via the Manipulative Bitch's Dark Magical Girl daughter, who pulls a Heel Face Turnfirst and brings him along. (Genderflipped example, then?).
The same way could apply to Ravness Loxaerion, the new girl. When Duke Ronwey turned Heel, Denam/Catiua/Vyce's turn of Face/Heel depends on the player's actions. Leonar always turns Heel, Ravness ALWAYS TURNS FACE. Though depending on your decision, she might not enjoy that Face status soon.
Time Splitters: Future Perfect. The time traveling hero helps out a seventies super-agent stop a world threatening conspiracy. Many of the female mooks can be overheard desiring the super-agent in many sexy ways. Gamewise, here is no choice but to shoot the mooks. The super-agent? More interested in dressing up like a lady and flirting with the men in the game.
Gitaroo Man is too weird to play very many tropes straight besides this one. There's only one female Gravillian, and naturally, she's been brought up to fight Gitaroo-Man as the planet's greatest champion, only to fall for him at the last minute.
Jinx from Teen Titans, the sole female of the HIVE Five group, ends up joining the Titans in the end.
Rogue from X-Men: Evolution - although given that she was only on the bad guys' side because she thought the X-Men wanted her dead, this is pretty justified).
Zigzagged with Tabitha/Boom-Boom who leaves the Xavier Institute and moves in with the Brotherhood. She then leaves them when Mystique returns and works with the X-Men a few times after that. Actually, Boom-Boom never actually picked a side; She just hung out with whichever group was convenient, and even that didn't always mean anything. In one episode, she's staying with the Brotherhood while fighting crime with the female X-Men.
Averted in Kim Possible with Shego, who massively subverts the trope at the end of at least two episodes which look like they're heading in this direction. However, that doesn't stop her from taking part in numerous Enemy Mines, particularly in the finale.
Not to mention it's revealed she had done a Face Heel Turn in her background, inverting this trope, since she was the only female in her heroic Sibling Team.
In Wolverine And The X Men, Emma Frost betrays the Inner Circle out of a combination of her love for Cyclops and the fact that hanging around with the X-Men has caused her to grow a conscience, and, of course, the practical reason that the Inner Circle kept switching up their plans without telling her, making her feel like a betrayal was coming. This trope is averted by the Inner Circle's other female member, Selene, however; she's portrayed as an entirely unrepentent sadist and schemer throughout.
Parodied in American Dad when one of Stan's partner of the week invokes this to get them out of imprisonment with nothing more than a short song. He apparently sexed his way through 200 miles of jungles. Though to be fair... he did have an enticing voice.