If there is a character in fiction who is a Proud Warrior Race Guy who comes from a culture known for their high regard for "Honor," you will probably see a culture with great disdain for using ambushes, ranged weapons, attacks on the unaware, undefended, or the weak, or any sort of trickery.
While this can be true in fiction, this isn't actually true in our world. Actual Real Life Honor, as it was understood in Antiquity and heading into the Middle Ages, was more like what we'd now call "street cred." Honor and dishonor wasn't the difference between "fair" and "unfair" - it was the difference between "strong" and "weak." It was much less about chivalry and honesty and a whole lot about reputation and face. The point wasn't that you played fair; the point was that if anyone dared cross you, you'd kick their face in.
The origins of "Honor" probably come from nomadic or tribal societies, where there is no system that can be relied on to protect one's life or property, which are constantly at risk. There are no police, no courts, and no written law. The only thing governing people's behavior was "custom", and therefore one's reputation in the wider community was paramount, and the surest safeguard for oneself and family was having a fearsome reputation.
There was a very strong component of Might Makes Right; if someone called you a liar, you challenged them to a duel, and if they died, it meant that you were right, even if everyone knew that you were a liar. The Double Standard and Moral Myopia were stark and unashamed; a Cycle of Revenge was considered the natural and normal state of affairs. As the idea of "nobility" developed, honor became more exclusive, and noblemen were considered the only ones who could truly have "honor," and only between such men could questions of honor exist. If a nobleman felt a peasant or slave had impinged his honor, he wouldn't challenge him to a duel; such gestures were appropriate only for equals. He'd simply kill him on the spot, and probably have him tortured first (including the rest of his family).
The latest iteration of "honor" in Western countries is a weird hybrid system, which got influenced first by Christianity and later by Humanist values. In the classic sense of "honor", pity and mercy were synonymous with weakness. Butchering enemy women and children wasn't considered dishonorable. On the contrary, since at the time it was considered self-evident that women and children had no independent existence outside of their relationship to a man, their suffering (indeed their whole being) was considered important only in so far as it reflected on the man's honor. In wars between Native American tribes in North America, for example, killing a woman or child from an enemy tribe and taking their scalp was especially honored, as it showed one's bravery in having entered the very heart of enemy territory (where their families were kept). Raping a girl or woman was considered wrong not because of the trauma it inflicted on the actual victim, but because it dishonored the man who was supposed to have exclusive custodianship over her body (her husband, father, etc.). Killing or enslaving a man's family showed how weak he was and therefore how much stronger and better you were than him. If leniency was ever shown, it was never out of compassion but rather was either a gesture of respect towards the defeated man (if you felt he had acted honorably), or an indicator that you considered them so far beneath you that they weren't worth killing.
- Blazing Saddles. Sheriff Bart confronts Hedley Lamarr at the movie theater and tells him to go for his gun. Lamarr claims to be unarmed, so (following the Code of the West) Sheriff Bart throws away his gun and prepares to fight Lamarr with his fists. Lamarr smugly announces that he is armed and pulls out a derringer, whereupon Bart dives to grab his gun back and shoots him.
- In Discworld, the nobility/officer class have a tendency towards military flashiness and believing that a victory consisted in having less casualties than your opponent; the more total dead, the better. Tacticus, Vimes and Vetinari all avert this, preferring ambush tactics, psychological warfare, camouflage and stealth. Understandable since Tacitus only cared about conquest, Vimes is a policeman and a former street urchin, and Vetinari is an Assassin and political genius; neither of them is interested in fair play.
- In Captive Prince, this is a point of Culture Clash between the Akielon Proud Warrior Race, who believe in honorable combat, and the Veretians, who don't. Laurent is bewildered when Damen, an Akielon, informs an enemy Akielon general when to expect their attack, but the gesture helps them win Akielon allies later. The Veretians' attitude also trips them up, since their willingness to attack under a flag of truce leads Akielons to assume bad faith in anything they do.
- In Star Trek this is a common plot point when dealing with Klingons. A lot of human characters subscribe to honor of this type, and Klingons follow the traditional sort of honor (particularly through their love of ambush tactics). What throws a lot of characters off is that their main exposure to Klingon culture is Worf, and Worf as a Child of Two Worlds goes considerably out of his way to try and follow both, usually ending up on the side of this trope when there's a conflict. This eventually leads to a scene where Worf is forced to accept being stripped of his "official reputation" honor to preserve his "internal code of conduct" honor; he doesn't bother to clarify that he's using the word differently and it comes of as pure gibberish to the other Klingons.
- Ring of Honor's initial code was a mix of fair play and mandatory, unconditional, respect given to all competitors. Later variations of the code are more like Character Alignment. Christopher Daniels and his Prophecy were the most infamous wrestlers to vocally subscribe to a very different definition of honor, being hostile to the ideals of mandatory respect and level playing fields. Taeler Hendrix would also declare in a Motive Rant that sneak attacks against people you despise were very honorable, even if they disrupted the show and violated the ROH code.
- Dungeons & Dragons. The 1st Edition cavalier class was based on King Arthur and the Knights of the Round Table. They would not use missile weapons (e.g. bows or crossbows) and could not use burning oil against opponents in melee combat. In addition they had to follow a chivalrous code of honor, which forbade (among other things) sneaking around in disguise.
- Champions. The super villain Firewing had a code of honor that prohibited attacking by surprise, attacking from behind, or gaining an advantage (beyond his own abilities) that isn't also possessed by his opponent.
- Warhammer: the War God Ulric hates subterfuge and ranged weapons (except for ambushes).
- In Warhammer 40,000, Space Marines, as a rule, hate camouflage, stealth, or hiding (they prefer shock and awe, which was very effective during the Great Crusade, but less so in the 41st millennium where many enemies can't be shocked or awed), with the exception of the non-canon Reasonable Marines, who are sporting in that they will give diplomacy a fair shot, and cut fair deals, but who, once you leave them no other choice, will kill you, unceremoniously and anticlimactically, and the canonical Raptors chapter.
- Khorne zigzags this: on the one hand, any blood spilled in battle is his, be it from enemies, allies, yourself, or defenseless civilians. On the other hand, his throne sits upon a mountain of skulls taken from warriors- again, yours or your enemies, but not defenseless enemies. Decapitating an entire orphanage or hospital ward and claiming their skulls as trophies is a surefire way to get his hellhounds after you.
- In Ironclaw the Overconfidence Gift allows you to offer an opponent a bonus d12 to their roll against you, if they accept you take a bonus d12 as well.
- In Quest for Glory II, a Fighter player will end up getting into a duel with The Dragon Khaveen during the endgame. At one point you'll knock Khaveen's sword out of his hands; if you want to be able to become a Paladin, you have to let him retrieve his sword rather than just killing him then and there. The situation is reversed earlier in the duel, and Khaveen is shown to be a royal slimeball because he absolutely will kill you while you're defenseless, meaning you have to dodge his attack and retrieve your sword in the same motion.
- The Order of the Stick: Subverted when The Paladin Miko refuses to ambush a group of ogres, instead walking into their camp and challenging them all... to get them all in one spot for the Order's spellcasters to wipe out with fire and lightning. The Order start out out infuriated by her apparent Honor Before Reason and end... conflicted.
- Unsounded: Duane, a powerful spellcaster and experienced combatant, refuses to use magic when he fights a non-mage guardsman. He explains to the Combat Pragmatist Sette that it would have been an unfair advantage, but brushes her off when she points out that he also has undead Super-Strength and resilience on his side.