Eddard "Ned" Stark from A Game of Thrones is such a classic example, this trope could easily be called 'The Ned Stark', hence the comic on the main page. The series being highly cynical in outlook, this is a tragic flaw which leads directly to his own death, his daughter's captivity, and his son's armed rebellion.
Eddard's son Robb Stark unfortunately inherits this trait. Despite his pledge to marry a Frey lady to seal his alliance with the Freys, he marries another woman, to save her honor after sleeping with her, shortly after Frey men died fighting for him, which eventually leads to them betraying him. So does Ned's bastard son, Jon.
Hell, Ned's beyond-rigid honor ends up possibly doubly affecting them negatively. Not only did Robb and Jon inherit the trait itself and its downsides, but it's possible that Jon is not actually Ned's bastard son, and Ned lied about this fact to protect Jon and possibly honor a promise to keep this secret. He honored this promise so intently he didn't even tell his WIFE the (maybe) truth, even YEARS LATER. So Catelyn ended up hating Jon, because Jon was living evidence her husband cheated on her, which Robb picked up on, which made him determined not to father a bastard, which meant he broke his bargain with the Freys to marry the first girl who slept with him to make absolutely sure he didn't father a bastard, which led to the Red Wedding and Robb, Catelyn, and thousand of other deaths. Way to go, Ned. Nice job breaking it doesn't even begin to cover it.
The Karstarks (actual distant relations) are just as bad, if in a different way. They have honour, and are prickly about maintaining the letter of it. To the point of taking umbrage when Robb has to execute one of their members for, frankly, being a grief-stricken, convention-breaking idiot which causes most to turn coat instead of acknowledging the whole "stewardship of the North" thing the Starks have going on may occasionally lead to conflicts of honour like this. The insanity snowballs towards a major in-family fight over who will inherit their own titles, let alone anything else, at a point in time when the bigger seasonal picture is not that healthy for anybody not being able to pull together as a whole. Well done, Karstarks: you can shoot yourselves in the feet about as well as Starks can.
Subverted in the case of House Arryn. Honor is a trait of House Arryn and it's heavily implied that the only reason the Starks are so honourable is because Ned was fostered with Jon Arryn, but by the beginning of the series the only Arryn's left are crazy Lysa and her sick five year old son.
The Kingsguard are sworn to protect the king, no matter how bad he may be.
The Night's Watch must defend the realm from anything beyond the wall and stay out of any political entanglements. Jon Snow tries to mobilise the Watch to rein in the warring kingdoms before the Others return, and gets stabbed for it.
Stannis Baratheon, too. He doesn't even want to be king, but he's going to fight for it because to his way of thinking, he's the rightful king whether he likes it or not. For the same reason, he refuses to ally himself with competing kings Renly or Robb Stark even though he badly needs allies against the Lannisters.
In David Wingrove's Chung Kuo, members of the House (the parliament) have the son of the T'ang of Europe killed. Knowing where this could lead, the T'ang decides to let matters be. The leader of his army, Marshal Tolonen, does not obey orders. Instead he marches into the House in session and slits the throat of one of the plotters. This sets the stage for everything else.
Kel from Tamora Pierce's Protector of the Small. In particular, she goes into enemy territory with the intent of rescuing 500 refugees. By herself. This is so likely to end with her death that she herself acknowledges it. Admittedly, if she hadn't, then the refugee children, two hundred of them, would have been made into nigh-unstoppable killing devices, but that doesn't really enter into her reasons for why she does it. Fortunately, her True Companions anticipated this and go to fight with her. They are a more understandable version of the trope; they still face exile/execution for betraying orders when they return to Tortall, but at least it won't be for nothing: they have a decent chance of defeating the Big Bad, and evening out the war.
Horton The Elephant from Dr. Seuss is an elephant of unshakable honor; once he gives his word, nothing will make him go back on it regardless of much danger, humiliation or rejection he suffers. Fortunately, his stories always end with him coming out on top because of this sense of honor.
Piers Anthony relies on this one a lot. Given that the promises are often given under extreme duress ("Swear it or I kill her" or "Swear it or I will never let you leave"), one might think the promises meant little... oh no. Even if it endangers the free world, or the universe, that promise will not be broken, no matter how much Angsting goes on because of it.
Self-lampshaded in later books: male centaur "character" (the refusal to go back on one's word) is "stubbornness" to everyone else, especially to the level-headed and practical female centaurs.
This is actually subverted in his Mode Series. The villain, well aware that the male lead will never go back on his word, agrees to let them go free, if they agree not to interfere with his plans. What he didn't take into account was that the female protagonist and her psychic horse don't play by those rules and the moment they are free, the horse uses his powers to force said villain to relinquish his claim to the multiverse, thus trapping him in his own world. The male lead is upset about this, but ultimately can't do anything about it now.
Averted in His Dark Materials: It is Will's opinion that honor might make you feel important, but when fighting is a matter of life or death, you have to fight dirty.
Especially when you're twelve, and going against grown-ups.
In Empire of Ivory Laurence cannot abide High Command's act of sending a Typhoid Mary among the French aerial corps — an act which probably would win the war for England, but would just as likely also result in genocide among Europe's (and possibly Asia's) dragons. So, in an act he knows will see him hung, he steals some of the curative mushrooms they'd gathered from Africa, and goes AWOL to deliver them to the French. In a further act of Honor Before Reason, he turns down Napoleon's offer of asylum or safe passage to China, preferring to return to England and face the music. Temeraire, getting in on the act, refuses to let him return alone. Laurence urges him to return to China, because he knew Temeraire was destined to be used as nothing but breeding stock if he went back. He doesn't. And the book ends with them flying back together.
Admiral Rolandlampshades this in the fifth book by pointing out how this verges on Lawful Stupid: he could have sent a discreet letter to Napoleonanyone in France telling them where to get the curative mushrooms; someone as ingenious as Napoleon could easily have bribed a servant for a sample. This would have prevented High Command's act of genocidewithout anyone knowing it was him.
Which only comes after he stops another (Prussian) character from shooting Napoleon from cover, but this may be not thanks to honor but his reasoning that Lien would have mauled them if they'd killed Napoleon not, which would have stopped them from revealing the French's plans they had just overheard.
Wanderer, a parasitic alien who co-inhabits the mind and body of a human named Melanie in The Host is very pro-life. She lies, badly and obviously, in order to protect the life of a guy who repeatedly tried to kill her. In fact, she's so pro-life that when she realizes that being a parasite on intelligent species is wrong, she would rather let herself die than be transplanted into another body and take away their free will. Fortunately for Wanda, her friends (a) disagee with that, and (b) found her a replacement body that was as close to her ethical standards as possible.
Carrot Ironfoundersson, the six foot dwarf (adopted) of the Discworld series is this to a "T". The weird part, though, is that, for Carrot, it works.
But the weird thing is, if anyone else tried it, they'd get creamed. It only works for Carrot because he's, well, Carrot.
More specifically, because he's a prince in disguise. Presumably if he acknowledges his heritage and takes the throne, he would start running headlong into all the challenges of a corrupt, decadent city like Ankh-Morpork and be frustrated in everything he tries to do. The Theory of Narrative Causality will support him constantly as long as he's an underdog but rightful leader, and not a minute longer.
This is an example of The Code, a set of rules followed by heroes that says when a hero who follows the code is hopelessly outnumbered he will win. Also when the silver horde (seven old men) win a battle against five armies and when six men (some of them from the silver horde) who had just broken into the city of the gods back down from Carrot on the grounds that he's a king in disguise and there's one of him and six of them. Cohen the Barbarian sums this up perfectly "I outnumber you one to two."
Another Discworld example from Jingo: 71-Hour Ahmed got his name from averting this trope. In the desert people are obliged to give one another three days of hospitality; the bond between guest and host is sacred, and considered inviolate by even the most seasoned killer. Ahmed was the guest of a man he suspected of poisoning a well, and thereby killing an entire village. After seventy-one hours he had put together the evidence necessary to prove his host's guilt, and Ahmed saw no reason why justice should wait even one hour — and so his host became a head shorter. Ahmed became feared even by the D'regs, who despite being viewed as untrustworthy, bloodthirsty, and deceptive have their own code of honor.
In Snuff Vimes has reluctantly acknowledged that whatever his faults, Lord Rust is a man of honour, and it's just a shame he confuses honour with pig-headed stupidity. In a sort of warped mirror of how things work for Carrot, Rust valiantly led charges against an outnumbering enemy, and somehow his bullet-headed conviction that he can't be killed because he's acting honourably acts as armour. Shame about the men following him, though...
Galad Damodred, from Robert Jordan's 12-book trilogyDoor Stopper bookshelf-destroyer fantasy series The Wheel of Time, always does what is right, no matter the cost to himself or others. His half-sister considers him loathsome for this reason. He also joins the series' version of the Knights Templar, which created similar opinions in readers. This actually works in his favor in Knife of Dreams when he challenges an opponent knowing that his opponent was the better swordsman only to win because his opponent was dragging out the fight to make Galad suffer. The result is that the Knights Templar now follow him.
This seems like something of an informed ability (or maybe "informed personality trait"?). Throughout the books, Galad is usually willing to help most of the other characters that cross his path, or at least doesn't look to deep into things when they blatantly lie to him. He's avoided the soul-scarring spiritual and mental anguish pretty much every single other person has to deal with, and has managed to purge most of the evil elements from his fanatically-loyal army, while getting them to drop their centuries-long "Magic is Evil" crusade in favor of fighting the true Big Bad. For a series that is all about tragic flaws, Galad seems to make his work.
Also, there's the Ogier, who'll never go back on their word, a fact exploited by Faile in The Shadow Rising in order to force Perrin to take her with him to the Two Rivers.
Refreshingly averted in Honor Harrington (even though you'd be forgiven for mistaking the trope name for one of its titles): most main characters, while definitely being persons of honor, hold those who enter the Lawful Stupid territory due to this in the very low regard. Especially the title character, who once suffered a command officer that tried to use this trope to cover his incompetence.note Said commander, later made an admiral, got his comeuppance during Haven's Operation Thunderbolt, albeit at the expense of the fleet he commanded and the world it was assigned to guard.
Although played completely straight by the Planet of Hats Montana, filled with rugged individualists who all put honor above reason. In fact, their chief law enforcement officer is open about the fact that if he felt strongly enough about resisting the annexation of the Talbot cluster, he would resign and fight it openly like his erstwhile friend rather than continue in his job where he is immensely respected.
Honor herself is generally pretty honourable (appropriately enough!) — she just makes sure when she gives her word that she either really means to keep it or phrases it so carefully that she technically didn't break it (as in Honor Among Enemies).
It is played straight a few times where it is outright stated that making a heroic sacrifice to uphold the Star Kingdom's honor is a part of the Navy's tradition. Or in other words, getting your ship destroyed rather than be seen retreating is regarded as stupid but getting your ship destroyed attempting to protect civilians or an allied planet is simply following in the tradition of Edward Saganami. Michael Oversteegen sums it up:
"Well," Oversteegen said with a cold, hungry smile, "defendin' other people's planets against unprovoked attack by murderous scum seems t' have become something of a tradition for my Queen's Navy over the past few decades. Under the circumstances, I'm sure she'll forgive me for followin' that tradition."
Romance of the Three Kingdoms has Liu Bei, who nominally honors this trope (for political correctness' sake, apparently with Confucianism and thus this trope being en vogue). Subverted in that more than once he operates less than nicely, whereas other times Honor Before Reason's the reason that he's the protagonist.
For example, his refusal to simply take over Jing province before Cao Cao's arrival, even when Zhuge Liang specifically calls him on it, is because it would be interrupting the "natural" succession to the eldest son of current governor Liu Biao, and he doesn't want to take any criticism from "the people" for it, even though the dying Liu Biao himself requested that Liu Bei be his inheritor. In an earlier case of this with the late governor Tao Qian of Xu province, the late governor's officers and people begged Liu Bei to accept the succession... and even after Liu Bei gave in, he soon tried to give the office away to Lu Bu.
Dynasty Warriors 7 had a variation where Liu Bei similarly refused to usurp his relative and host Liu Zhang of Yi province — even though controlling Yi province was the key step in his advisor Zhuge Liang's "Tripartite Realm" strategy — leading to his other advisor Pang Tong, and his generals Huang Zhong and Wei Yan, "mutinying" against Liu Zhang on behalf of Liu Bei and "the people," leaving Liu Bei upset until he saw that "the people" seemed to be perfectly fine with this.
In J. R. R. Tolkien's The Lord of the Rings - The Two Towers, Aragorn makes a statement fitting this trope when the Brothers-in-Arms have gone into Fangorn in search of Merry and Pippin.
Gimli: Then what shall we do now? We cannot pursue them through the whole fastness of Fangorn. We have come ill supplied. If we do not find them soon, we shall be of no use to them, except to sit down beside them and show our friendship by starving together. Aragorn: If that is indeed all we can do, then we must do that. Let us go on.
In The Silmarillion, the Oath of Fëanor is particularly problematic: the eldest sons of Fëanor feel compelled to fulfill their oath, even though this means doing things which are not only counterproductive but which they know to be utterly wrong.
That's pretty much the plot of the Quenta Silmarillion: The hubris, stupidity, and irrational stubbornness of the good guys, especially the elves, does at least as much damage as Morgoth himself.
Denethor also accuses Faramir of this in The Return of the King, though unfairly. (Denethor feels that the Ring would have been useful to his country in the war, while Faramir believed it was too dangerous to use and therefore did not take the opportunity to get it from Frodo.)
"Ever your desire is to appear lordly and generous as a king of old, gracious, gentle. That may well befit one of a high race, if he sits in power and peace. But in desperate hours gentleness may be repaid with death."
Bilbo in The Hobbit refused to kill Gollum out of pity, when it was clearly the sensible thing to do, as did Frodo (and eventually Sam) in the sequel. These actions led to the eventual saving of Middle-Earth, even when they seemed completely illogical at the time.
In The Dresden Files, the purpose of the Knights of the Cross is not to kill Denarians, but to save their hosts. They will give their foe every chance to surrender the coin, only killing the host if there is absolutely no other choice. And if the host does surrender the coin, their job is done, no matter how evil and vile the host may be, or how likely they are to seek another coin — their purpose is not to judge, but to give each host a shot at redemption. Oddly enough, it does seem to work out for the best: Sanya, Knight of the Cross and wielder of Esperacchius was a former Denarian host. However, also subverted — Michael and Sanya walk away from a particularly nasty host who had surrendered his coin in order for his life to be spared. However, they didn't insist that Harry do the same, and Harry, being the nice sort of chap he is, proceeds to break every major joint in the host's body with a baseball bat in order to extract important information and stop the host from escaping. And afterwards, the two Knights have a good laugh at the expression on the host's face when he realized he was left alone in a hotel room with a violently angry and vengeful man.
On the side, they're especially amused by the fact that Harry gave the man a quarter to use the pay phone to call 911.
Michael: Phone calls cost more than that now. Harry: I know. Everyone:(raucous laughter)note In most locations, 911 is a free call, even from a payphone. Harry was just being evil.
Considering that said Denarian knew that the Knights wouldn't touch him because he surrendered the coin, regardless of the reason; then, before Harry beats the crap out of him, talks about how they tortured Shiro, the third Knight, and threatens Susan, the same woman Harry started a freaking WAR over... Of course, it deserves to be mentioned that the same Denarian host comes back two books later in Dead Beat while working with the main villains, and tortures Harry in an attempt to get Lasciel's coin.
And the way Harry pulls off this attack on the Denarian is perfect.
I turned away from him again and said, very quietly, "People like you always mistake compassion for weakness, Michael and Sanya aren't weak. Fortunately for you, they're good men."
In Sir Apropos of Nothing,, the titular Anti-Hero has no use for honor, and often uses other people's honor against them in strange and awesome ways. Well, sometimes. Okay, when he's backed into a corner.
Another Warhammer 40,000 novel example: Soul Drinker. Sarpedon's refusal to back down and let the Adeptus Mechanicus get away with stealing the Soulspear (which was the most sacred relic of their Chapter, and they had only just managed to locate it) led directly to their being declared Excommunicate Traitoris and finding themselves chased around the galaxy pursued by both Chaos and the Imperium, perpetually depleted and subject to shoot-on-sight orders.
In James Swallow's Warhammer 40,000 novel Deus Encarmine, Stele indulges in Flaw Exploitation with this; because the Blood Angels believe they owe him, he sets into play a Batman Gambit to win them to Chaos. Unfortunately, he trusts it a little too far. When he hears a message had been sent bearing the id of a dead sergeant, he is flabbergasted: the Blood Angels regard tampering with the equipment of the dead as sacriligeous. He does not consider that it is forbidden except under the most dire circumstances and so does not investigate who could have gotten to the dead man's gear. Indeed, when the responsible Blood Angel confesses, those he confesses to regard it as very serious — but not so serious that even investigating it should take precedence over the news he had sent.
In P.C. Hodgell's Chronicles of the Kencyrath, the Kencyr peoples display this trait as a whole. Honor overrides reason and common-sense, although the cleverer Kencyr are very good at working out ways to keep within the Law while doing whatever they want.
In The Belgariad, the Arends have this as their hat. Mandorallen takes this to the extreme even for an Arend.
This is also the hat of the Tsurani from the Riftwar Cycle, interestingly, both the heroes and villains of the Empire Trilogy, that takes place entirely on the Tsurani homeworld, are people who realise that the Tsurani definition of honor should be put aside in the pursuit of more pragmatic goals. For the bad guys, it's selfish desires, for the good guys it's the good of the Empire in general.
The Knighthood as a whole was doing a-okay right up until the Cataclysm. In the aftermath, the public began turning against them, saying that the Cataclysm was either their fault or blaming them for not stopping it. Solamnia was spared much of the destruction that followed, but soon Knights of Solamnia were being murdered by mobs in the streets. Recruitment plummeted and many remaining Knights simply took off their armor and renounced their vows. The larger problem was that the Solamnic Knights were sworn to uphold the Code (seen above) and the Measure, a complicated series of laws that uphold chivalric virtues and knightly behavior. For centuries, most of the Knights' senior leadership posts were vacant because not enough Knights existed to constitute a quorum to vote in new leaders and the Measure made no allowances for a giant meteor wiping out a good chunk of their membership. It wasn't until after the War of the Lance that a revised Measure was drafted that was much more flexible with the formalities. But during the War of the Lance, a large percentage of the Knighthood was slaughtered because they were ordered into a hopeless Curb-Stomp Battle by a half-insane Knight of the Rose, Derek Crownguard. They could not refuse, because the Measure made Lord Derek the commander by rank and seniority, nor could they remove him from command because the Measure did not anticipate a Knight commander losing his shit in the middle of a war.
It was his last triumph over these lunatics to go down into their dark room and die for something that they could not even understand.
In Edgar Rice Burroughs's The Gods of Mars, a traitor offers John Carter his freedom in return for certain pledges, and even though he will die, and his friends and allies could really use his help, Carter refuses.
In The Chessmen of Mars, when a man tries to lay hands on her while she is a prisoner, Tara stabs him, much to the horror of a slave woman.
Lan-O, wide-eyed, looked with horror upon the corpse. "For this we shall both die," she cried. "And who would live a slave in Manator?" asked Tara of Helium. "I am not so brave as thou," said the slave girl, "and life is sweet and there is always hope." "Life is sweet," agreed Tara of Helium, "but honor is sacred. But do not fear. When they come I shall tell them the truth — that you had no hand in this and no opportunity to prevent it."
In A Fighting Man of Mars, Tan Hadron rues this: John Carter refuses to strike first in any war, but his enemies, this time, had a Mad Scientist invention that caused ships to disintegrate and men to fall to their deaths, horribly; it had a short range, and Heliumite guns could have pounded the enemy ships to pieces before being in danger.
Doing this is the central theme of de Sade's Justine. It is, however, satire.
The Bronze Horseman by Paullina Simons. Alexander and Dimitri plan to desert during the Finnish War by volunteering to search for their commanding officer's missing son. When they really do find him while crossing the lines, Alexander insists they bring him back, earning Alexander the eternal gratitude of their CO, and the hatred of his friend Dimitri.
This attitude gets Bertie Wooster into (light comedic) trouble on a regular basis.
In Wen Spencer's Endless Blue, Paige says that they can't provoke a fight with the civ, as they are intelligent if primitive, Jones says that's inconvenient, and Paige says it's not supposed to be convenient.
Byrhtnoth Byrhthelming, hero of the Anglo-Saxon poem The Battle of Maldon (fought in 991), has a horrible case of this: the Saxon army is on the mainland, the Viking enemy are on a marshy island with a one-man-wide causeway as the only way off, the Viking leader says that a really honourable opponent would let them cross and fight on open ground... and Byrhtnoth agrees. The Saxons are crushed and he dies.
YMMV here, as he may have suspected that if he didn't let them fight on open ground, they'd merely sail off and raid the next town over. He had the largest force in the area, and thus the best chance to stop the raiders, making this more of a Senseless Sacrifice.
A similar dilemma to the last John Carter example above led directly to the utter destruction of a galactic civilization in the past of the Perry Rhodan universe: Segafrendo. Picture a galaxy very much at peace with itself and ably defended against external threats by scarily competent alien mercenaries who everybody knows can nonetheless be trusted utterly because of their adherence to a strict code of honor. A code of honor that, it turns out, prevents them from initiating any hostilities against others on their own no matter how much they might want to. Cue a massive invasion force from another galaxy showing up and clearly moving into the perfect position over multiple worlds for its own crippling first strike, all the while refusing to formally declare its intentions or fire a single shot until ready...
Sharpe's Honour, shockingly enough, features this as a major element. It starts with Sharpe fighting a duel over the honour of a woman he knows to be a traitor. Half-way through he's offered the chance to escape captivity, foil his nemesis and save the war for Britain, but refuses because doing so would involve breaking his parole (which he has not, at that point, given).
In Shadows of the Empire, mercenaries burst in on Luke Skywalker and some Bothan spies. One of the spies is shot but not with an Instant Death Blasterbolt, and Luke refuses to leave him - and the Bothan dies, and Luke is captured, while those Bothans who just ran got away.
Allegiance has Leia in an Imperial city and lying low, because they know she's there and are hunting her. While in hiding she sees burglars breaking into a house that has a child in it; she knows they probably won't just let the kid be, so she fires her blaster, even knowing that patrollers might hear and investigate. She knows it will get people's attention. That's why she does it, even though she might be discovered because of it.
Garren's father in the Farsala Trilogy, who made a bet that his son could conquer Farsala with only ten thousand troops. Unfortunately, his son has no such scruples.
Eremon in Jules Watson's Dalriada Trilogy. He refuses to turn on the Scots tribe he's only recently met in order to join the Romans, even though it would be in his best interest to do so. Since there's no apparent reason why he'd be so loyal to the rather ungrateful tribe, this comes across more as a plot device than anything else.
Colonel Nicholson in The Bridge Over The River Kwai orders his men not to attempt an escape from the prison camp, because the circumstances under which they were captured mean that it would technically be against the rules for them to escape. He also helps his captors build a better bridge because they ordered him to.
It should be noted that Percy's fatal flaw is personal loyalty, which is basically an extreme version of No One Gets Left Behind - ie. he'd prefer the safety of his friends and family over the safety of the world.
While The Zombie Survival Guide advises you to travel through urban areas as quickly as possible and not stop except under dire circumstances, an exception can be made if you want to assist other survivors. "Sometimes, logic must give way to humanity." (The rest of the book averts this pretty hard, though, and encourages the reader to be as pragmatic as possible for the sake of their own survival.)
The Elites in the Halo expanded universe often would rather die with honor than live without. In The Cole Protocol it's even dishonorable to have another Elite give you a mercy killing, implying you're too weak to even kill yourself.
Some are even observed fighting in hand-to-hand combat and dying from it rather than pick up a fully loaded human weapon at their feet.
In a bit of a departure from human concepts of honor, Elites find it dishonorable to be wounded in battle, meaning you weren't good enough to come out unharmed. The Elite dishonorable in this manner usually demands to be allowed a chance to redeem himself by shedding blood of enemies. In The Cole Protocol an Elite feudal lord is attacked in his bedchamber by assassins. He kills them and, the next day, shows up in front of his vassals and disrobes to show no marks on his body. He then kills the man who sent the assassins for not doing the honorable thing and coming after him himself.
In one of Mercedes Lackey's Tarma and Kethry stories in Oathblood, Tarma and Kethry (and their Kyree Warrl) get a bad-luck cursed coin. Kethry refuses to do anything to pass it off onto another innocent party. Warrl comments, "Admirable. Stupid but admirable." They eventually get rid of it by arranging to be targeted by bandits. Kethry only refused to pass it to an innocent party.
The Arkenites in the Star Trek Novel Verse take their debts very seriously. In the Star Trek: Vanguard series, Klingons save an Arkenite outpost from a disaster in exchange for the outpost swearing allegiance to the Klingon Empire; the residents then refuse to back out. Even though they don't want to leave the Federation or help the Klingons, they all willingly keep to the promise even when Starfleet shows up trying to "liberate" them. To choose gratification over duty and refuse to repay their debt would, their leader explains, be unthinkable.
Rudolph Rassendyll of The Prisoner of Zenda loves Princess Flavia and is loved by her, and she is arranged to be married to her boorish cousin and The Wrongful Heir to the Throne. Rassendyll admits to himself that the best possible outcome would be allowing the villains to dispose of his look-alike relative before stopping them, allowing him to be a good ruler and be with the woman he loves. However, because of his honor, he helps restore the king to the throne and does not get the girl. For her part, because of her own honor, Flavia accepts being married to a man she despises rather than one she loves.
Michael from the Knight and Rogue Series. He will only lie if absolutely necessary, and lets a murder suspect run free even though doing so will give him one of the most severe punishments the law can deal because he's found evidence she's innocent. In fact, she flat out tells him she can prove her innocence in court, but he's worried because the court he wants to take her to is stacked against her and there's a chance she could be found guilty anyway. Just for added affect, this not actually guilty murderer who choses not to capture despite the penalty had been torturing/experimenting on him several hours before he made this decision.
In Michael Flynn's The January Dancer, the two owners of the only ammunition factory burn it down to keep the civil war a fight with blades. Then they shake hands and depart for opposite sides of the war. The one who joins the coup is regarded as odd by his own side, who do not understand his principles.
In Wen Spencer's Tinker, Windwolf threatens to castrate the man who offered Tinker a Scarpia Ultimatum to treat Windwolf. It would have stained his honor, even though it might cost him his life.
Kazem too. Lots of 'die on your feet then live on your knees' sort of lines from him. Whether he believes this himself or is just using it as propaganda is up for debate.
King Joyse in Stephen Donaldson's Mordants Need novels. He refuses to take action while his enemies plot against him for fear that the cost of victory will be too high, using a problem from a draughts game that can't be won without sacrificing pieces as a metaphor for his dilemma. He also refuses to prevent his subjects from taking actions that have tragic results because they're motivated by love of the kingdom and have earned the right to do as they see fit. Subverted in the end though, since his inaction and feigned indecision were all part of a Xanatos Gambit he was playing against the whole world.
Ashinji of Griffin's Daughter. He basically swallows the heaps of abuse and petty slights his Jerk Ass older brother drops on him solely because Sadaiyo is the heir to the throne and Ashinji "owes" him fealty. Even his parents (who are aware of Sadaiyo's... predilections) marvel that he hasn't at least beaten the crap out of him once.
Though usually a very pragmatic series, Animorphs pulls this one out of left field during the David Trilogy. The titular character is a Sixth Ranger the Animorphs have narrowly saved from capture, who in the process has been completely cut off from his family, his home, and everything he's ever known. Normally a pragmatic bunch, the Animorphs suddenly become unyielding sentinels of morality in dealing with him, forcing him to sleep in a cold barn rather than letting him sleep in a hotel room (which he admittedly broke into). Jake even goes so far as to threaten David's life, which is especially jarring when one considers how often the other members of the team have used their powers for selfish ends. With all this dumped on him, it's really no surprise when David snaps and goes Sixth Ranger Traitor on them.
In The Decision, all the Andalites on a ship decide to collectively commit suicide rather than running away when it becomes clear that they can't defeat the Yeerks the way they'd hoped. This was Lampshaded in Cinnamon Bunzuh!:
Ifi: You can morph too, dude
Ifi: Did you forget that you can morph?
Ifi: You can all morph.
Ifi: You can ALL morph.
Adam: Isn't escaping the honorable thing to do?
Ifi: Not as honorable as MASS RITUAL SUICIDE
In John C. Wright's The Hermetic Millennia, Oenoe recounts how some Nymphs, insanely, did not love their world of total indolence and ease, even with the help of drugs. Men were offered cryogenic slumber until the age where more martial virtues were needed, and women turned into heralds who sought out those men and brought them to the sleep. Oenoe herself slept in the tombs because she was in love with one such woman, and preferred having her heart break to forgetting her love.
In The Trumpeter of Krackow, a legend is told of a trumpeter who is sworn to blow a trumpet from a church tower every hour, doing so even while the Mongols are ravaging his city, thus revealing his presence. As might be expected, he ends up shot with an arrow for it.
In Redeeming Love, Love Martyr Michael Hosea’s attempts to cure bitter, cynical, and manipulative Broken Bird Angel, who is a prostitute—by marrying her and treating her as he would a pure, devoted, and faithful wife—often cross over into this territory, especially in the view of the other characters, who urge him to forget she ever existed.
Horatio Hornblower fights with this trope at times, dickering over doing the honorable thing vs. the logical thing and angsting over his decision later. He plays it straight a couple of times as a Plucky Middie, when he tries to refuse being transferred from the Justinian* a Channel-bound tub to the Indifatigable* an active frigate with certain opportunity for career advancement out of loyalty to Captain Keene; Keene is touched but scolds him and sends him off anyway. Not long after that, Hornblower refuses to take credit for stopping a privateer he was held prisoner because he "lost" the prize vessel he had been commanding. (It had been holed—not Hornblower's fault—and had a rice cargo, so it basically popped its seams and became unsavable.)
In The Lost Fleet, after 100 years of brutal fighting, The Alliance fleet has degraded to this, although their concept of honor has also "evolved". Fleet tactics have largely been forgotten, as every ship charges into battle and hopes to win through sheer "fighting spirit". For the same reason, commands of choice are no longer battleships but battlecruisers, which allow them to be on the forefront of any charge. Battleships are reserved for those who lack aggression, with the thought being that thicker armor and stronger shields will help to compensate their faults. Killing civilians en masse is perfectly normal in order to deny the enemy further recruits and ruin the economy. Prisoners of war are executed. Saluting is an archaic concept, except for Marines. When Captain John Geary is recovered from his Human Popsicle state, he is horrified to learn what has become of the Alliance sailors and officers. He tries to reintroduce the concepts of fleet tactics and honorable behavior, while constantly arguing with those ship commanders who want him to lead them to victory without changing anything. It doesn't help that most expect him to be the legendary "Black Jack" Geary whose last recorded order was "close with the enemy" (it was actually his Last Stand in an attempt to let civilian ships escape).
In Dangerous Spirits, Konstantine falls just short of considering any criticism against the Tsar to be nothing less than outright treason, and breaks several friendships by reporting them to his superiors when his compatriots comment that the Tsar, while a great man, does not have a God-given right to rule.
Played straight for cynicism in The Prince of Thorns: Jorg is an almost-heartless monster who kills and tortures without hesitation or moral qualms. In the sequel The King of Thorns, his foil the Prince of Arrow is an honorable man, who even gives Jorg the chance to surrender and refuses to kill him because he's still a boy. As repayment, Jorg starts multiple avalanches on his army, his newlywed wife blows up the invaders who've gotten through the gate as well as their own defenders, he allies with trolls, and finally Jorg attacks the army with all of his necromantic and fire magics until both are burned out of him and the army is routed. But none of this really matters, because the honorable Prince of Arrow has already been killed by his own less-honorable brother.
During A Brother's Price Jerin gives his word of honor that he will be a placid, willing captive if his captors will spare Cira. He promptly turns on them, explaining to Cira that this is dealing with these people on their level - they're already shown themselves to not be trustworthy in the least.
In the first pages of Tyrannnosaur Canyon Tom Broadbent promises a dying man that he will convey a notebook and message to the dead man's daughter. He takes this promise personally, not allowing the police to get involved when they might have been able to help and directly imperiling his friends and family.
This trait is ingrained into the training of the Disciples of Penance from Of Fear and Faith. The group of them that the party meet in the Fortress of the Damned refused to abandon their station even long after it became clear that they were fighting a losing battle, and so they became trapped there, which did not end well for them. When they finally escape with the party's help, their leader Giovanna elects to turn herself in to her superiors to be arrested for leaving her post, and all of her soldiers follow her due to a combination of this trope and Undying Loyalty to her.