Oliver Twist by Charles Dickens has one of the characters –- the ruthless Bill Sikes, the town bully –- beats many people, including his prostitute girlfriend, Nancy. Despite his abusive behavior, Nancy stays with him, believing she is a stable force in his life. In the end, she sees that he is nothing but a despicable person and leaves him to take care of Oliver. Bill, in one of the most heinous acts of 1800s English literature, barbarically kills Nancy. It isn't long before Bill is caught and put to death ... this despite his taking Oliver hostage.
The Saint: Simon Templar usually doesn't apply his personal brand of justice to women, but this was mainly due to a little trope known as High-Heel–Face Turn. When he did, in fact, shoot a couple of women (the leaders of a drug ring), he notes that this is the first time he's ever actually done so. On a couple of other occasions, he has no compunction about hitting a woman carefully on the back of the head to knock her out for a while.
Females in Warrior Cats are functionally equal to males. You'll find females leading Clans, females leading patrol parties, and females suffering the same wounds. The only time they're given special mercy is if they're pregnant.
Even the "mercy for the pregnant" has been averted once to give Breezepelt a Kick the Dog moment.
During a Quidditch match, Oliver Wood tells Harry to stop being a gentleman and just knock Cho Chang off her broom already. Chivalry might not be his only problem there — his crush on her is revealed in the next book.
In the fifth book in a Roaring Rampage of Revenge Harry tries to torture Bellatrix with a curse. It doesn't have enough power behind it and only knocks her off her feet.
Harry disarms Narcissa Malfoy in the seventh book.
Gentleman Bastard Locke Lamora is willing to punch out an eighty-year-old woman. She's the Magnificent Bitch head of the Duke's spy ring, who had stabbed Locke with a needle dipped in a slow-acting poison and was offering the antidote in exchange for selling out his friends. He didn't have time to trick his way out, so he went for the direct method. It's implied that the reason this worked is because he is known for his brains, not brawn, and it never occurred to her that she might not be safe alone in a room with him.
In Splinter of the Mind's Eye, pretty much anyone is willing to hit Leia. Grammael does it to get Luke to talk. Vader cuts her in their duel — yes, she fought him with a lightsaber, and though she came off worse it wasn't a Curb-Stomp Battle. Even Luke hits her, slapping her when she's very agitated and about to blow their cover by leaving.
Legacy of the Force: In this series of books, Jacen Solo ends up killing at least 4 female characters. Apparently, the three authors working on that series subscribed to the idea of Wouldn't Hit a Girl, and used this trope to demonstrate how much of a monster Jacen had become.
In Ceremony, Spenser and Hawk fight their way through an orgy. Hitting men and women alike, Spenser comments, "No sexist, I".
In the Sword of Truth series, at various points Richard has pointed out that he's perfectly willing to fight women, as he knows they can be just as dangerous as men, if not moreso.
In Game of Thrones, Viserys frequently threatens Daenerys, who lives in terror of 'waking the dragon'
King Robert punches Cersei in the face in a drunken rage.
King Joffrey does believe that a King should not strike his lady, a 12-year-old Sansa Stark. Instead, he has his knights of the Kingsguard do it in his stead. With gauntlets.
Ramsay Snow's treatment of his many female prisoners along with both of his wives has been used to characterise him as a monster.
Taken to an extreme in Mickey Spillane's I, the Jury: Mike Hammer deliberately shoots Charlotte Manning, a woman, in the stomach to avenge the similar murder of his Army buddy. Although this is sometimes passed off as self-defense, because she was secretly reaching for a gun at the moment of the killing, Hammer had already explicitly told her that he intended to kill her, and thus it is her actions that may be self-defensive.
Interestingly, one exception occurs in the book Hide and Seek. Jack Emery was rescuing Lizzie Fox from the FBI, and Lizzie wanted him to rescue Judge Easter from them, too. Jack tried to point out that they needed a plan to rescue her and that they could not just charge back out there. Lizzie, refusing to be amenable to reason, makes the ever-so-mature decision to pull a gun out on Jack to make him help her rescue Judge Easter now. Jack managed to knock her out with a karate chop to the back of her neck. He did send a silent apology to her later on for that.
John Chai from Vendetta.
Karl Woodley from The Jury.
Maxwell Zenowicz from Fast Track.
Given that the Honor Harrington novels are set far in the future, gender equality is considered normal in most of the galaxy. Plenty of the people that are killed on all sides are female. Notably, the planet Grayson is a giant aversion to this trope under most circumstances.
The Millennium Trilogy has Lisbeth Salander (and a few other women) being repeatedly attacked by men who do not hold back at all. This is not all that surprising, as one of the main focuses of the books is the abuse of women by men. Holding back against Lisbeth would not be a good idea at all.
Sort of, in Galaxy of Fear: The Brain Spiders. Eventually Zak attacks his sister Tash, punching as hard as he can - he's only twelve, but she's only thirteen. It's "sort of" because this is only Tash's body, which is being controlled by a man who is still "he" in pronouns. "It was Tash's face he was hitting, but his blows were rattling Karka's brain."
The three male leads, Rand, Mat, and Perrin, are from a culture where violence against women is pretty much unthinkable. Yet each of them eventually finds himself in a situation where killing a woman is necessary, and each regrets it severely: Rand meets a darkfriend on the road in the third book, who tries to lull him so assassins can get the drop, and he responds by killing the entire group. He later develops a severeWould Not Hit a Girl complex and when facing Lanfear is unable to use deadly attacks even though it may cost his life. Mat is seduced by Melindhra and kills her in defense; after this, he goes to great lengths to avoid fighting women, even when it puts him at a disadvantage, but is not as intense about it as Rand. And in the last book, Perrin has to kill Lanfear to prevent her killing Rand in his moment of triumph. Because of the mind control she's placed on him, he's deeply in love with her at the time, but still manages to bring himself to attack out of need.
The whole of the Seanchan and Aiel cultures, where women can join armies/warrior factions, same as men. The one exception are Aiel Wise Ones, whom nobody is supposed to hit, and they aren't supposed to participate in fighting either.
Perrin has a few "I pray these aren't women I'm killing in battle" moments, but he's nowhere near as bad as Rand, or even Mat. He also defends himself against his violence-equals-love girlfriend. In his defence, he has a fear of hurting people in general because he's so beefy and strong, and sort of part wolf. The spirit of one, anyway.
The male Asha'man on the whole, and especially Logain have no qualms about attacking female Aes Sedai, even if Rand forbids them from killing them.
A woman leading a band of male bandits/darkfriends in book 3 is advancing on Mat, who seems to be refusing to defend himself, when Thom throws a knife into her heart. He also fits into Wouldn't Hit a Girl though, because Moiraine notes his reluctance to politically move against women, even the ones who are more dangerous and treacherous than the men.
Galad, surprisingly enough, comes to this conclusion, earning a rare bit of praise from his sister and saying one of the most sensible things about men and women in the series:
Perhaps once I would have hesitated [to kill a woman], but that would have been the wrong choice. Women are as fully capable of being evil as men. Why should one hesitate to kill one, but not the other? The Light does not judge one based on gender, but on the merit of the heart.
In Breakfast of Champions, Dwayne Hoover, during his rampage, says, "Never hit a woman, right?" before punching Beatrice Keedler and Bonnie MacMahon, who were trying to restrain him.
In Ruth Frances Long's The Treachery of Beautiful Things, Tom tries to persuade Jenny that Jack is nothing like them, Jenny sneers that neither she nor Jack are like him, and they're blessed in that, and he hits her. A fight with Jack ensues. Jenny is more horrified because of their blood relation than this trope, but it does play some part.
In Julie Kagawa's The Iron King, Quintus captured Meghan while the other four fought Ash. When he goes to torment Ash, Ash counters that he's the coward who wrestled with a girl while the other fought.
Tsagaglalal is attacked by Spartoi warriors in the sixth book.
Dragon In Distress has Sir George, who threatens to use force against Princess Florinara Tansimasa Qasilava Delagordune. Apparently, his knightly vows did not include 'and not harm women'.
A Mage's Power: When a female mage throws lightning at Eric, he responds in turn. Then he goes on to repeat the feat against his other female oponent in the New Scepter Competition's tournament.
In Midnight Tides Trull Sengar, a warrior, asks a healer, who in his culture are exclusively female, to heal a demon. She refuses on the grounds that it's not worth the effort as they can always conjure more and earns a nasty back-handed slap. Trull Sengar is made to apologise to her reasoning that he was stressed from the battle just past, but he insists that he feels no remorse, as for him anyone who fought should also be worthy of healing.
In Vampire Academy, Strigoi apparently believe in beating people up equally. They don't mind attacking females physically. Goes with their lack of morality.
Dan Krokos's False Memory has this exchange:
Peter: You didn't break my nose.
Miranda: Too bad.
Peter: No, that's good. Because I would've broken yours.
Miranda: You'd hit a girl?
Peter: We fight all the time.
In The Sword-Edged Blonde, part of Canino's Establishing Character Moment is to viciously assault his girlfriend Gretchen, who he apparently had a good relationship with (and who certainly didn't see it coming, or understand the reason for it). He did it just to make a point to Eddie — if he's willing to be that needlessly brutal to a girl he mostly likes, how much worse is Eddie going to have it?
Finally, in a Crowning Moment of Awesome in Misery, Paul Sheldon slams Annie in the face with a typewriter. (She was trying to kill him at the time, so it's warranted).
There are just as many girls as boys in of The Hunger Games, ensuring a lot of this. Marvel kills Rue, and Thresh kills Clove.
In Radiance, it's implied that when the filming of the documentary at Adonis began to fall apart, one of the crew members attacked Severin. It later turned out he did so to try to keep her from swimming with the callow whales, which was incredibly dangerous and led to her death. The transcript of her impromptu reporting on the Pluto food riots also have her beaten and bloody and end with her trampled nearly to death by a mob too enraged to even notice her.
Alexis Carew: Anybody who fights Alexis—Captain Grantham actually complains once about how often she ends up beat to hell—but special mention goes to the horribly sexist Captain Neals, who is only stopped from having her flogged on general principles by the fact that he legally can't flog an officer. Then he disrates her for refusing to beg forgiveness on bended knee for not identifying a man who made a minor mistake due to fatigue, and promptly gives her two dozen lashes. This triggers a mutiny.
Gor: Tarl Cabot starts out seeming unwilling to hit women, though he does threaten them with serious harm at various points. By the sixth book, Raiders of Gor this reluctance has vanished entirely and he doesn't hesitate again to strike a woman for defiance, or to have her beaten.
Zig-zagged by the Confederation in Victoria. One of their worst enemies is a Lady Land, and they show few qualms about crushing their female troops in the field. Once victorious, however, they treat their civilians unusually nicely by their own standards; even irreconcilable bitter-enders are condemned to slavery when captured, rather than simply executed after drumhead court-martial.
Landslide by Desmond Bagley. When the protagonist gets his face slapped by a Spoiled Brat he slaps her right back, figuring there's no point in applying a Double Standard in this day and age.