Keldorn and Jaheira from the Baldur's Gate series have shades of this, the former being a 60+-year-old paladin and the second a very cynical Harper (a secret society devoted to spreading good).
Tom from Bendy and the Ink Machine: In the game, he and Allison live in a world filled with monsters, a world in which they cannot trust strangers. They still rescue a stranger, Henry, from being killed - twice (although they do lock him up at one point because Tom doesn't trust him). Tom contrasts with Allison in that he's a jerk to Henry and isn't the type to paint the word HOPE on the walls. He also contrasts with Sammy and the Lost Ones because he has maintained his moral compass in refusing to worship the resident demon or participate in Human Sacrifice.
Anonymous from BoxxyQuest: The Gathering Storm is a snarky, foul-mouthed Troll who likes starting arguments and treats the adventure like a bad joke… but he’s also Catie’s truest companion, who never backs down from doing what’s right, and would never think of turning his back on the party when they need him. In fact, he’s the one who pulls Catie herself back from the Despair Event Horizon not once, but twice during the course of the story.
Gabriel Belmont Castlevania: Lords of Shadow also qualifies. As his mentor Zobek explains, he could have given up all hope of saving the world because he has done so many questionable deeds, which he himself admits so. However, something in his mind still forces him to continue on and keep doing good, albeit bitterly ...
Even after becoming Dracula, the sequel reveals that he still fights for the world despite his hatred of it. Specifically, by being the apex predator that keeps other eviler but less powerful villains in check.
Corruption of Laetitia: Celeste realizes that she may be considered a hero in the short term for defeating Marian, but the world may eventually consider her a nuisance or symbol of fear. She also doesn't consider herself a heroine due to no longer seeing the conflict as black and white. Despite that, she states that she needs to defeat Marian because he's definitely a villain.
Cyberpunk 2077: Johnny Silverhand, to a fault. Johnny has never wavered an inch from his anarchist, anti-corporate ideals, even in the face of death. However, he is also severely disillusioned with the people around him and their willingness to accept the status quo even when it doesn't benefit them in any way. The fact that his natural personality is abrasive enough to make sandpaper look like silk by comparison doesn't help, but by the time of the game he has alienated pretty much all his friends, his fans and everyone around him when they wouldn't buy into his cause as deeply as he did. Not that it stopped him from continuing the struggle, even for people who don't appreciate it.
From Dead Rising, Frank West, a freelance photojournalist with a rough attitude and a determination to set things right in the zombie-infested world.
Devil May Cry series protagonist Dante based on his tragic past. His family troubles and basically living in endless poverty has a "live-and-let-live" sort of view on justice. Dante basically lives life on his own terms and besides devoting his life to stopping demons, he's a jerk with a snappy one-liner ready to distance his involvement with getting to close with people and barely has a care for the world outside of stopping the demonic invasion of the week. Regardless, he will still fight the good fight.
Keisuke from Devil Survivor becomes this if you can convince him he's wrong after he snaps.
Alistair fits this trope well. He literally stopped short of becoming a Knight Templar and instead devotes his time trying to hold onto his ideals and do what's best for everyone, regardless of his own growing cynicism from how ungrateful people can be.
His fellow tank warrior Aveline from the sequel also fits; she's a world-weary widowed soldier and cop who's seen a lot of bloodshed and suffering and whose goal is to protect her friends and keep what order she can in the world.
Also a natural fit for an elf Grey Warden—humans have been bastards to you, your family, and your race for longer than they can remember, and don't exactly feel guilty about it. The game demands that you save the mostly human kingdom of Ferelden, reunite it under legitimate political authorities, and generally leave it a much stronger and more powerful nation than it was before you entered the picture. One bit of dialogue has an NPC thanking you for saving the kingdom, and one of your responses is along the lines of "I'm saving my people from the Blight. Your kingdom can burn for all I care."
Varric Tethras fits into this trope in Dragon Age: Inquisition. In the beginning, he outright states that he's pretty sure the world is going to end no matter what they do, but he stays and helps anyways. By the end, should you play your cards right, he changes his attitude a little by believing that the Inquisition, with the Inquisitor leading them, is the final, best hope for Thedas, but he still acknowledges that the world is in a bad situation.
Hawke can fall into this, especially Snarky Hawke: they've lost friends, family, siblings, they've had a ton of crap dropped on them, and while they'll drop sarcastic asides at every opportunity, they'll still force themselves up and go and do the right thing.
Dragon Quest Builders paints the Hero from Dragon Quest as having had shades of this. One of the guards in Tantegel will make remarks about how he questioned why none of Alefgard's actual knights were making even an attempt to help him, and even criticized the King for such sheer inaction. It's effectively given through Elle's hypothesis that being groomed to exist solely to defeat the Dragonlord and living a life of But Thou Must! led to this jaded edge, and why he would ever accept the Dragonlord's obviously raw deal in the first place.
Several characters in Fallout: New Vegas qualify for this. Rose of Sharon Cassidy is a hard-drinking and somewhat surly woman who also happens to have a strong moral code, being the one character who will specifically complain about the player's Karma Meter if it gets incredibly low. Also, there's Colonel Hsu and Chief Hanlon of the NCR, who despite being personally against the war (especially considering the fact that their commander, General Oliver is a Glory Hound and General Failure) do what they can for the sake of the soldiers
Orion Moreno and "Cannibal" Johnson are also good examples, especially Orion. Both were former members of the Enclave. At the destruction of their oil rig, the New California Republic dismantled the Enclave, seeing them as too great a potential threat to ignore. Decades later, the NCR finds itself up against Caesar's Legion, a group of totalitarian slavers. Moreno sympathizes with the Legion, unable to forgive the NCR for defeating the Enclave, which he considered the last remnant of the old America (and he's kind of right). Johnson supports the NCR, seeing their democratic government to be in the spirit of the old America and preferring them to the brutality of the Legion. Both men can be convinced to join the final battle—but serving the wrong side will require a very difficult Speech check—Johnson will abandon you rather than fight the NCR, and Moreno will try to kill you—after donning his Powered Armor and hefting a minigun.
Squall Leonhart from Final Fantasy VIII veers between this and just being a Jerkass (later revealed to have a Hidden Heart of Gold because Love Redeems.) Especially notable because doing the right thing, for him, means not only fighting for a world he might not think is worth fighting for (most of the game, anyway), but also serving the forces which have forbidden him from exercising his free will for his entire life. (Though, to be fair, he has been strung along most of the time because he doesn't know what he would do otherwise)
Lightning in Final Fantasy XIII is a female example. She does believe in doing what's right, but the world she lives in is so messed-up she has very little "right" to believe in and she bitterly laments her fate as a cursed l'Cie.
While we're on the subject of Final Fantasy XIII, how about Sazh and Oerba Yun Fang? Sazh's only desire is to see his son again and he's willing to turn himself in to see his son one last time before he is executed. Vanille is what keeps him going. The same is said for Fang when it is revealed that she was a Pulse l'Cie before the start of the game along with Vanille and cracked Coocoon's shell as Ragnarok. By extension, the entire main cast if you go by their backstories and their cursed fate as a l'Cie. Even Genki Girl Oerba Dia Vanille who lied to everyone about being a Pulse l'Cie so she could help them. Had she not lied at all, things would have gone differently.
Cody from the Final Fight, and later Street Fighter series is a perfect example. In Final Fight, he was a straight-out Hero, who fought the Mad Gear Gang to rid his city of them and rescue his girlfriend Jessica. Along the way, he beats up a corrupt cop named Edi, who later has him arrested for assault and battery. While in prison he develops an addiction to fighting, and when he gets out, walks the streets looking for the slightest provocation to fight. After he is thrown back into prison, his girlfriend leaves him and travels to Europe, her father Haggar is all but through helping Cody, and only his best friend Guy still believes in him. By the time of the Street Fighter series, he believes that he is no longer a hero and that the only purpose he has left in the world is to fight, which he frequently tells everybody is meaningless. However, he still has some desire to protect the world, as he breaks out of prison to seek out villains like Bison and Seth to defeat, and his theme implies he wishes to relive his glory days of heroism, but has convinced himself it is too late.
In Fire Emblem Fates, the Avatar becomes this in the Conquest route, and develops some shades of this in the Revelations route. In the Conquest route, their wide-eyed naivete is slowly crushed by the bitter experiences throughout the route (though does nothing to shatter their resolve to see their mission through). In the case of Revelations, they mostly have elements of Knight in Shining Armor, but because of learning the truth behind the conflict, and the fact that there is a bigger threat in the form of Anankos, they become no longer naive about the happenings of the world anymore and their naivete is tempered by wisdom.
Genshin Impact: Rosaria genuinely believes in Mondstadt's principles and desires to protect the city but has been jaded by her line of work to the point that she lacks faith in the gods.
Ryudo from Grandia II fits this trope to a tee, in reaction to the original title's protagonist, Justin, who was an idealist with a strong wanderlust — almost Sonic the Hedgehog in human form. In the sequel, Ryudo is a misanthropic mercenary who wants nothing more than to escort his charge (a sickeningly cheery do-gooder, Elena) from A to B and collect his reward. He's also a bit of a smartass, always ready with a sarcastic remark. The game goes down the usual JRPG paths, peeling back the onion to expose Ryudo's reasons for distrusting everyone and everything, and revealing his kinder side from time to time.
Manuel Calavera of Grim Fandango is a cynical man who claims to only look out for himself. When he joins the LSA and heads out across the Land of the Dead to search for Mercedes, he claims it's only because she is his ticket to the next world. However, he does thaw somewhat over the course of the story, as particularly evidenced by his relationships with Meche, Glottis, and the Angelitos. As Grim Fandango was based on several Film Noir classics including Casablanca and Double Indemnity, this characterization fits the milieu perfectly.
Canach from Guild Wars 2. He made some bad choices in the past, but he's trying to make up for that by helping the Commander fight the elder dragons and save the world. That said, he is still holding onto his salty attitude, making him fit solidly into this trope.
Gwent: The Witcher Card Game: The Northern Realms pack a lot of knightly units with big swords and shiny armor, but their vocal callouts pack a lot of bitterness and sarcasm.
Redanian Knight: Long live etcetera etcetera...
Cole MacGrath from inFAMOUS. If you finish the game with good karma, he ends up as Empire City's savior, but the final scene has him musing about his isolation (given that his girlfriend is dead and his best friend's betrayed him) and wondering how long it will be before the city turns against him. Unfortunately for him, he knows that there's something big and powerful coming, and he's the only one that can stop it. He's not happy about it at all.
Pit from Kid Icarus: Uprising is a cheerful and optimistic angel who does his best to protect humanity and serve his Goddess. He's also well-aware of the flaws of every side of the War by the end of the game, noting that Humans Are Flawed and that the Gods are certainly destructive and selfish in their own right, but chooses to believe that humans are worth protecting and that his Goddess is worth serving, all the same.
Jolee Bindo in Knights of the Old Republic has rejected the Jedi Order as hypocritical and hidebound, but he hasn't rejected his moral center. Carth Onasi fits the trope as well. He's closer to good on the Karma Meter than the Jedi in your party, but his capability to trust in the good of others has been torpedoed by personal tragedy. He's vocally suspicious regarding the player character and the entire situation; that suspicion eventually turns out to be eerily dead-on. The comics, set a few years before the events of the game, make it clear that his entanglement with Revan wasn't the first time he found himself involved in a Jedi scheme and cover-up.
Lancelot from Labyrinths of the World 12: Hearts of the Planet devotes himself to protecting his underground world despite coming off as unsympathetic because of it. He comments at one point that he doesn't have to like people in order to help them.
In L.A. Noire, Herschel Biggs and Jack Kelso are both perfectly aware of and disappointed in the state of the Los Angeles, and how little of what they do is actually meaningful. They try their damnedest anyway. Protagonist Cole makes the shift from idealist to sour knight over the course of the game, despite his attempts not to, thanks to the corruption and politics endemic in the LAPD.
Agate from The Legend of Heroes: Trails in the Sky is a perpetually angry young man who especially at first has nothing but scorn for the heroine and her extremely optimistic outlook. In spite of the misanthropy, he's one of the best Bracers in Liberl. Originally, he Used to Be a Sweet Kid until his little sister died during the war, making him channel all his anger into fighting, not helped when he joins a gang in Ruan until he got the crap beaten out of him by local Greater-Scope Paragon Cassius. He softens up a bit after befriending the preteen Tita, who he became fond of after she went out of her way to protect him. He eventually becomes even less sour when Loewe of all people deconstructs that mindset as regressive. If he just uses his sword as a crutch to channel his anger, he'll never be able to move past his weakness and find enlightenment. Yet he's too sentimental to fully make use of his vengeance as a tool, not a crutch and commit to villainy. That, and an effective speech from Tita to trust her as a friend, and not his sister's replacement.
Yakuza 4 protagonist Masayoshi Tanimura is well aware that the police department is full of shady people, himself included, and would much rather slack off than follow protocol, but he'll still help the public when needed and is a selfless person at the end of the day. He's surprisingly idealistic underneath his apathetic demeanor, which is partly why he reacts so badly to his superior Sugiuchi being a yakuza spy who murdered his father.
Yakuza 5 protagonist Tatsuo Shinada is deeply embittered due to false accusations getting him permanently banned from his dream of being a baseball star. That said, he's still a kind person who goes out of his way to help others, and is determined to preserve the idealized image of baseball for the sake of its fans.
Hasshe from Live A Live. After defeating the Lord of Dark, he was heralded as a hero, but the very nature of human beings continued to disgust him much to the extent that he faked his death and hid out in a cabin in the mountains, only being convinced to help Oersted save humanity again because, despite his hatred, he knows that it's the right thing to do. When he dies, he asks Oersted to believe in his friends and not become bitter as he did. Unfortunately, the outcome of Oersted's own adventure eventually pushes him far beyond merely being bitter.
Garrus from Mass Effect falls into this, especially in the second game. He starts a vigilante group on Omega to help combat the crime, corruption, and decay of the station, and admits that he knows he wasn't really making a big difference; for all of the irritation he gave the mercenary groups after him, Omega was a pisshole when he started and was a pisshole when he left. And he fights on anyway.
Shepard can be played like this if you act douchey in dialogue but ultimately do good things. If you have a Colonist background, the Asari consort says as much, 'detecting a sadness behind your eyes'.
Wrex turns out to be this if you befriend him. He's old enough to remember his species in their glory days and has become very cynical as all his efforts to reverse their self-destructive slide to extinction have failed due primarily to Chronic Backstabbing Disorder. But if he survives the first game, he decides that there is reason to hope for the future and returns to his homeworld to give the krogan another shove at being better than just a bunch of thugs-for-hire.
At the end of the Lair of the Shadow Broker DLC, Liara will ask Shepard how s/he's doing. If you choose the right dialogue option, Shepard will vent about how tired s/he is of dealing with Cerberus and the Council treating him/her like s/he's nuts. But in the end s/he keeps going because s/he wants to give people the chance to change for the better.
Shepard: People are messy, awkward, sometimes selfish and cruel. But they're trying, and I'm going to make sure they have a chance.
By Mass Effect 3, Shepard has embraced this trope and taken it up to eleven. S/he vocalizes at MANY points in the story his/her doubts that anything s/he does is actually going to win the war but s/he never stops going.
Javik could also be turned into this, depending on Shepard's choices.
Max Payne. His entire family murdered, his best friend killed, and both the good sides and the bad sides of the city trying to kill him. He even contemplates leaving the city early on, becoming a fugitive, but quickly decides that he'd rather see things through to the end. He ends up paying for it pretty harshly, though.
In Metal Gear, Solid Snake is arguably the best example in gaming. He's cynical, jaded, world-weary, really couldn't care less about being seen as a hero or a legend, and doesn't believe he'd make a difference to the future ("I'm not as arrogant as that."), but he continues to fight because no one else can or will.
Snake:"I'm no hero. Never was, never will be. I'm just an old killer, hired to do some wet-work."
His papa, Big Boss, is another example until his Face–Heel Turn, particularly after being forced to kill the Boss.
The Boss herself is, knowing that a soldier's calling is not something they can decide for themselves but must be heeded regardless, though she takes it better than her protégé or Solid Snake do (she's learned to suppress the "sour" and accept things as they are).
Neverwinter Nights 2: Casavir also behaves like this sometimes. Just try asking him about the circumstances of his first exit from Neverwinter.
Marshal Leigh Johnson of Red Dead Redemption is a bitterly jaded old man who nonetheless remains steadfastly good throughout the game (though by the epilogue he moves as far away from Armadillo for his retirement). John Marston has similar tendencies when he decides to help out people (mostly Bonnie and Luisa), to the point that Abraham Reyes refers to him as a "romantic trying to be a cynic".
Chris Redfield of Resident Evil fame expresses such views in the the fifth game; with bioweapons running rampant and in the hands of terrorists since Umbrella's fall, Chris actually wonders at times if fighting against bioterrorism is even worth it. Taken to another level by Resident Evil 6 where Chris starts to drink heavily on a near daily basis after seeing most of his men get slaughtered on a mission they were on. Chris starts to believe that nothing he does will change anything. but it takes some bonding time with his partner, Piers, to get Chris back to his fighting spirit and shed the sour armor.
Sakura Wars: Yoneda's introduction to Ogami, in a drunken stupor, says it all:
Yoneda: A hero? No kid; I'm just a filthy old bastard who got badges for murdering a lot of people.
Shadow the Hedgehog eventually becomes one. He went from fighting against the world to fighting for himself, to fighting for the world. Pretty much his only reason for this is because a little girl told him to before she died. It took Shadow a while to remember that, but when he did, the bad guys began wishing he was still one of them. When one of the villains tries to bring Shadow over to his side by telling him that the world will turn on him one day, Shadow simply responds by saying he'll fight like he used to.
Gerald Robotnik. Since he's an old guy, he can't really fight, but he knew that humanity was good and deserved saving. So what did he do? He created an immortal, powerful hedgehog named Shadow to protect humans, despite that Shadow pretty much hates humans, calling them "pathetic" at every chance he gets. Bonus for Gerald in that he pretty much hates humans just as much as Shadow, although this may be because the aforementioned little girl was his granddaughter, and her death made him go insane, considering how she'd been killed because experiments to save her had been considered too dangerous. However, when he was sane, he reveals to Shadow that he built the gigantic gun on the ARK station to actually save the Earth from an alien attack that would happen 50 years later, while Shadow previously thought that he had built it to destroy Earth. Guess who pulls the trigger?
Siegfried Schtauffen from the Soul Series started off as a delusional young man on a quest to find his father's killernote Really he did it himself by accident when he and his band of thugs attacked a camp they thought was housing army deserters, believing that taking up the sword Soul Edge will allow him to accomplish it. It didn't and it turned him into a slave of the sword, becoming known as the "Azure Knight" Nightmare and slaying countless individuals to feed the sword's lust for souls. However he does eventually free himself from it and becomes a remorseful, driven man who believes his life is worth nothing if he can't put an end to Soul Edge as penance for his sins. Unfortunately, this one-track mindedness leads him to do some questionable things and also makes him a prime target for seduction by the Soul Calibur, the counterpart to Soul Edge.
Star Wars: The Old Republic has Keeper (later known as the Minister of Intelligence) in the Imperial Agent storyline. He joined Imperial Intelligence hoping to do some good for the Empire, only to be blocked by red tape and Sith interference at every turn, and usually forced to just make things worse for people. Years of this have led to him becoming a massive cynic. Still, he keeps on trying to use his power to do the right thing. In the end, he finally gets the chance to do some good, helping the Agent destroy the Star Cabal and giving the Agent the option to use the Black Codex to wipe out all evidence of their existence, abandoning Imperial government in favour of acting as a sort of freelancer, helping the Empire wherever help is needed.
It's also very easy for the Imperial Agent themselves to become this, as a result of the Trauma Conga Line they can have to endure. Many players find their Agent becoming increasingly less idealistic and more disillusioned with the Empire, similar to what Keeper went through.
Kratos Aurion in Tales of Symphonia fits this like a glove. He started out as an idealist alongside Mithos Yggdrasill who just wanted half-elves to be accepted, and then became what we see in the game.
Colette: Our weapons are love! Genis: Justice! And... Kratos: Sigh...hope.
Yuri Lowell from Tales of Vesperia left the royal knights because he felt they were doing very little to change the lives of the poor and downtrodden and end the corruption among the upper class, but his sense of honor and justice still drives him toward this goal.
Garrett from Thief fits this role well. He's a completely unrepentant criminal who acts as though he has nothing but contempt for others, his surroundings, and the whole corrupt, depraved pit that is the City and the world he lives in... most of the time. But there are hints that Garrett cares more than he'd ever want to or admit when he witnesses cruelty against almost anybody, especially the poor and already downtrodden, and even people who've tried in the past to kill him. (Possibly because it's a really, really long list.)
Aiden Pearce of Watch_Dogs could be seen as a deconstruction as, while he deals with his grief over letting his niece die by trying to clean up Chicago, the level of drivenness one has to have to chase after something like this has many consequences that you need to turn a blind eye to if you want to keep going. Innocent people often get hurt during his deeds, he has become violently unempathetic, and the idea that his family will be whole again once he completes his mission only ends up putting them in harm's way and causing a deep rift when he ignores his sister's pleas to stop causing them problems.
Jack van Burace from Wild ARMs is very cynical and abrasive, especially towards Cecilia due to her royal background, but he does his best to protect his companions. His sourness comes from being a former knight of Arctica, a kingdom destroyed by the demons. A mixture of grief and guilt drives him to seek revenge in the hopes of putting the past behind him.
This is probably the defining characteristic of Geralt of Rivia from The Witcher. As a mutant monster hunter, Geralt is hated by almost everyone and knows it since they mock him, spit on him and violently attack him just for being what he is. As a witcher, he is solely supposed to work for money killing monsters. That said, he is an actual knight, just one who barely uses the title if at all. Despite always telling himself and others that he only works for money and doesn't want to get involved with normal people or politics, Geralt seems to have one of the worst cases of Chronic Hero Syndrome of any character anywhere, constantly putting his life on the line for people who don't care if he lives or dies. This exchange from the third game solidifies it:
Neku Sakuraba from The World Ends with You eventually grows into this as a result of his Character Development. He's rude, incredibly sardonic, and is initially only driven by his own desire to survive no matter what, but he'll do the right thing more often than not and even saves Shibuya thanks to his growing idealism and willingness to change for the better.
