Finn from Adventure Time occasionally falls into this. He nearly has a nervous breakdown in "Memories of Boom-Boom Mountain" trying to make everyone happy because he made a vow to always help someone in trouble, and in "Videomakers" he insists on obeying the FBI warnings on all their pre-Mushroom War video tapes.
Anti-Villain Prince Zuko in Avatar: The Last Airbender begins the series believing he's a disgrace and only his father can restore his honour, with his rightful place, but his desperation and his tendency to put his quest for redemption above all else puts he and his crew at risk. He ends the series by wanting to restore honour of the entire Fire Nation. 'Kay.
Alissa from Dead Space: Downfall was more worried about helping the survivors (whom might already be infected) then quarantining the ship. Her captain might have been nuts, but he actually made SOME sense. Could also be a case of Compassion Before Reason.
You have to be dead in order to be infected, but still there was at most 20 people out of 2000 left alive and going crazy.
You don't have to be dead for the marker to drive you batshit insane though.
In the Futurama movie Into the Wild Green Yonder, the last Encycolopod tries (albeit reluctantly) to preserve the genetic material of the recently deceased last Dark One. The Encyclopod preserves extinct species by carrying recreations of them on its back using genetic material. The Dark Ones have been trying to exterminate the Encyclopods ever since the two species existed. If the Dark One's remains hadn't been completely destroyed before the Encyclopod could reach them, the Encyclopod's honor would have forced it to carry its own mortal enemy on its back.
In the Gargoyles episode "The Gathering", Goliath decides to have himself and his clan help their enemy, David Xanatos, stop the godlike Oberon from abducting his child on pure principle, considering they owe the billionaire absolutely nothing. Although it's obviously a difficult and dangerous task, Goliath is instrumental to making Oberon compromise to allow the child to stay. As a result, Xanatos then feels he owes the clan big time, which leads him to inviting them back to the castle to live safely after they are exposed to the public.
Likewise Owen's participation in that battle, since he knew Oberon would not be happy he was missing the Gathering.
During his first appearance Macbeth is trying to capture the gargoyles, but he chooses to calmly wait until sundown to fight them rather than just moving their statues in the middle of the day. In a later episode he refuses to let Demona smash them, again citing it as dishonorable.
In the two-part G.I. Joe: A Real American Hero episode "The Synthoid Conspiracy", Cobra Commander got a little tired of Destro's complaints, and in an attempt to put him in his place, made a Synthoid of Destro, simply to prove to him that he could be replaced. Destro would have none of that, and to show the Commander he did not like being insulted, betrayed the plans to the heroes (who were floundering and almost beaten at the moment; if this had not happened, Cobra likely would have won).
In Hellboy Animated: Sword of Storms, a Japanese daimyo kills his own daughter, rather than breaking a promise. A promise he made to demons.
Played straight and then subverted during an episode of the Iron Man animated series. Tony Stark agrees to get an artifact from a booby-trapped tomb if Madame Masque will release his kidnapped workers. She releases Julia Carpenter (Spiderwoman) who will send the Iron Man armor but keeps the other workers captive. Julia says that she will send down the armor "and a lot more", but Tony stops her because he has given his word. The trope is subverted almost immediately afterward. Once, Iron Man has entered the tomb, Julia convinces Jim Rhodes (War Machine) to attack Madame Masque and her minions anyway, arguing that the only chance the hostages have is if they attack their captors off guard.
During the Justice Lords arc, it's pointed out that the Lords are every bit as smart, strong, fast, and skilled as the League, except that they're willing to KILL. Superman insists that he won't cross that line, to which Batman replies they'll have to cross SOME kind of line. So they end up getting Lex Luthor's help.
Wonder Woman is banished by her mother from Themyscira for bringing men to the island and breaking the law. If she hadn't worked with the Hostage for MacGuffin scenario, the Amazons would remain in stone. If she hadn't received help from her teammates, Hades could have taken over. The Flash points out this is ridiculous since she risked her life to save everyone. When the Gods have her return in "The Balance", she says she should leave after completing the task. Hippolyta asks her to stay and when she points out her exile, her mother explains that the Gods will have to deal with her if they have a problem with that. One wonders why she didn't say this the first time other than to have a Bittersweet Ending.
Because she was too stubborn. In the first episode, she even told Diana they shouldn't be concerned about the alien invasion. Or it could be that the 'no men' law was laid down by the Greek gods, and they don't like being disobeyed.
In Kim Possible, Shego's brother Hego is this in the ep where it's revealed she used to be a hero. For example: His letting the enemy strike first and revealing their presence became too much for his sister, and became one of the many reasons, if not THE reason for her Face–Heel Turn.
Shego: (Annoyed) Why do you think I left?!
In The Legend of Korra, Korra publicly challenges Amon to a one-on-one duel, alone; Amon does not have the same moral qualms. And yet...
A weakened Korra challenges Kuvira but refuses to go into the Avatar State from the start, allowing the more highly-skilled and experienced Metalbender Kuvira to dominate the fight. By the time Korra finally relents and goes full Avatar, her Enemy Within rears up and forces her back to normal.
Particularly in the episode "Applebuck Season", where she promises to do a few too many things while also harvesting her family's entire apple orchard by herself. It takes most of the episode, severe sleep deprivation and overwork, and accidentally causing several disasters to finally convince her that maybe she should admit she's overextended herself and ask for some help.
She does it again in "The Last Roundup," where her failure to win a contest whose prize she had promised to donate to Ponyville led her to run away from home and go out West intending to work off the debt. She was too ashamed to face her friends and family, despite the fact that nobody else actually blamed her for losing the contest.
In "Phineas and Ferb's Quantum Boogaloo", when Doofenshmirtz took over the Tri-State Area in the Bad Future, he got everyone (including the O.W.C.A.) to swear obedience to him. All he had to do to stop whatever plans they had to dethrone him was reminding them of the oath.
Subverted in a strange way in a The Powerpuff Girls episode. Mojo has Blossom in a bind by having the Professor and her two sisters hostage. He demands Blossom's fealty and tries to use her honesty against her.
Blossom: What do you want? Mojo Jojo: First, you will bow down before me! Next, you will pledge your allegiance and devotion to serve me! Blossom: How do you know I won't lie? Mojo Jojo: Because you're Blossom. Blossom: Shoot!
Another example would be from the episode where she first gets her "ice breath" power. After inadvertently causing the escape of a trio of robbers, she promises never to use her ice powers again. She has the timing to make this promise as a giant meteor is headed straight for Townsville. She's the only one that can stop it, yet she's insistent on maintaining her promise despite the fact that the promise won't matter if she doesn't do something. Buttercup manages to snap her out of it, though.
When faced with elderly criminals, Buttercup and Bubbles prepare to foil their crime when Blossom stops them. She points out while they could stop them, they have to respect the elderly. She decides to instead recruit the heroes who fought the villains the last time. The end result has everyone being rushed into intensive care with everyone recognizing Blossom's error.
ZigZagged in ReBoot. Enzo has returned home to Mainframe, all grown up, big, strong and gunning for Megabyte, both literally and figuratively. When confronted by Enzo's gun, Megabyte taunts him into fighting like a "real sprite". Enzo puts away his gun...but then proceeds to send Megabyte flying with a punch hard enough to dent his chest, before Megabyte has a chance to prepare. And he then proceeds to do it again while Megabyte is still recovering from the first attack. When Megabyte inevitably cheats, he takes him on with a spear, then at the end of the fight, spares Megabyte... despite Megabyte enslaving the population of Mainframe, torturing his friends, and killing countless binomes.
Samurai Jack insists on defending others from evil, even when it means passing up a chance to return to the past and undo the original cause of the evil.
The 2013 Scooby-Doo video feature "Scooby-Doo! Stage Fright" has Fred and Daphne winning the top prize on a show called "Talent Star" via popular vote. However, they deliberately throw the contest so Emma Gale, a sweet little girl who was a contestant on the show, could win the prize and save her family's farm.
The Simpsons: Lisa turning down a fortune after finding out what Mr. Burns had turned the recycling company he and Lisa had started into. What she could've done with twelve million.
Homer, in a hospital bed after 4 simultaneous heart attacks: It's okay, sweetie. But we really could've used that 12,000 dollars. Lisa: Actually dad, 10% of 120 million dollars isn't 12,000, it's... *Smash cut to hospital corridor* PA: Code Blue! Code Blue!
The worst part about this particular scenario is that since Lisa didn't take the money, Mr. Burns gets the money, and he probably wouldn't do anything good with it.
This trope often applies to Lisa. Typically, someone will try and convince her to lie, cheat, or at least conceal the truth, because it's to everyone's advantage. In fact, the story will often go out of its way to assure us that everyone is better off with the lie. This usually leads to Lisa having a moral crisis before she decides to tell the truth after all (usually in an overly dramatic fashion). But of course, there's always another twist at this point.
In one episode, the town was Genre Savvy enough to trick Lisa. She had cheated in a test (no, really) and her ill-gotten A got the school in a position to be granted government funds. When Comptroller Atkins showed up at a public conference to deliver the check, Lisa confessed and Comptroller Atkins decided to let them keep the money anyway. After The Simpsons left, it's revealed to the viewers that, knowing Lisa would have confessed, the entire town had an imposter disguised as Comptroller Atkins to lure Lisa away and, when the real Comptroller Atkins showed up, they used a false Lisa to trick him.
Though in a surprisingly rare case it's averted in "Lisa the Iconoclast", where she ultimately decides not to ruin the town's image of their founder Jedediah Springfield by revealing that he was actually a ruthless pirate.
Star Wars Rebels: Appropriately enough, "The Honourable Ones" features this. After getting stranded with his archenemy, who's injured, Zeb has no real reason to let him live — except that Zeb would much rather beat Kallus in a fair fight instead of killing him out of hand. Kallus then ends up reciprocating it by saving Zeb's life when they're getting out of the ice cave, by choosing to shoot the creature attacking Zeb instead of him.
The Doom Patrol in Teen Titans are made of this trope; so much so that they come across as arrogant when they refuse to let the title characters join them on a potential suicide mission. This trope is also subverted in that the Teen Titans end up undoing all the Heroic Sacrifices the Doom Patrol made offscreen.
Thomas the Tank Engine has gained a heavy case of this in later seasons. While usually hard working and loyal, he will very quickly disobey an order or ignore duties if he believes someone else is remotely unhappy or needs help. He is usually reprimanded for this, though the Fat Controller occasionally lets it slide if it truly is for the better rather than just causing confusion and delay. Other engines occasionally have bouts of this too.
In the original Thunder Cats episode "The Slaves of Castle Plundarr", the mutants enslave humanoids resembling cattle. Lion-O, being Lion-O, wants to free them, and he and the elder ThunderCats do so. The mutants use "warp gas", an anger and aggression-inducing substance, to turn the freed slaves against their rescuers. Lion-O refuses to retreat, saying the Lord of the ThunderCats can't run. Cheetara tells him "pride carried too far is foolishness."
Brick from Total Drama believed highly in his code as a cadet. So strong was his honor, that he sacrificed winning a challenge for his team to save the lives of Mike, Zoey, and Cameron, who were on the other team. This resulted in his elimination, but those he saved saluted him good-bye.* In the Family Guy episode "Brian Goes Back To College", Brian goes on a guilt trip after Stewie convinces him to cheat on a test and pass. After some internal conflict, Brian decides not to cheat on his final exam and he fails, but at least he feels good for being honest. The Griffins all say he should have cheated.
Chris: I HATE YOU!!!
Optimus Prime in Transformers Generation 1 always was an honorable fighter. Particularly in the episode "Heavy Metal War", when Megatron challenged Prime to single combat. Megatron, of course, cheated by transferring all of the special abilities of the Deceptions to himself. Even though Megatron was clearly doing things he could not possibly do (teleport, fire null rays, etc.) Prime accepted defeat. At least, until Teletraan-1 pointed out what a cheating bastard Megatron was.
Many of the older comics and some of the new ones use this to mark the difference between Optimus Prime and other Autobot leaders such as Grimlock, who's not as honor bound, more ruthless and willing to do whatever is necessary for a victory. Yet that same honor, similar to Captain Carrot (see Literature, above) is what allows Prime to make things work that others simply wouldn't. Through patience, a few Peter Cullen Speeches, and honorable behavior throughout, Prime manages to convince a Decepticon commander that his surrender to the Earthbound Deceptions is not a sign that the "great Optimus Prime" actually is and always was a coward or a weakling, but rather that he genuinely believes that only by uniting can they stop a greater threat.
Omi in Xiaolin Showdown actually pulls a Face–Heel Turnbecause of this trope. Omi lost his good side temporarily becoming evil. The main villain of the season then had Omi pledge loyalty to him. After he returned to normal, Omi decided to stay with the villain SOLELY to keep a promise he made when he wasn't in his right mind.
Another is when Omi doesn't look up the secret to destroying all evil.... because he promised not to. And actually it's worse than that, because he DOES break the promise and looks it up... but now to feebly try to keep the now BROKEN promise he refuses to USE the secret. Sure, things work out in the better in the end, but it's still horrific use of this trope since as far as Omi was concerned, he was playing it painfully straight. Though it turns out the secret was really the secret to destroy all good. Chase gives up that little tidbit. Omi then uses Chase's own words against him.
Zeta from The Zeta Project is like this once he's grown a conscience and done a Heel–Face Turn against his creators. Ro notes that it would easier for him to escape the NSA's agents tailing him if he'd fight back, but his code of nonviolence is not negotiable for him. And on the odd occasions he will fight, he won't kill. Ever. The weird thing is that all of this actively goes against his programming and nature, unlike many of the examples on this page.