The manga version of Seto Kaiba is a cold individual who, during the Death-T arc, is revealed to have acquired his Blue-Eyes White Dragons through less than honorable means and climbed the ladder at Kaiba Corp rapidly which resulted in his adoptive father Gozaburo being Driven to Suicide; and treats Yugi and his friends with his utmost bitterness (he even outright says he's disgusted by their friendship). In the anime, Kaiba initially displays the characteristics of his manga counterpart, but eventually softens by the Battle City arc and even helps Yugi and his friends in key moments.
In Sonic X Dr Eggman starts off an Affably Evil villain similar to the games, before becoming more and more harmless, his scruples and respect for Sonic coming into play often, and spends most of the Third Season in Anti-Villain territory. This is even more prominant in the comic adaptation.
In the Ranma ½ manga, Shampoo was a cold, Manipulative Bitch who had no problem toying with Ranma, and even less so with wanting to kill Akane (though she's far from the only one in that regard). She still has a few shades of her manga counterpart in the anime, but she also shows much more genuine feelings for Ranma and goes out of her way to save Akane's life at one point.
In the Soul Eater manga, it turns out Justin Law was The Mole, working for Asura. The anime diverges from the manga shortly before this plotline comes up, thus such a revelation never happened.
Beelzebumon is one of the Seven Demon Lords in the Digimon series' mythology. In Digimon Tamers, he (as Impmon) starts out as a Wild Card, before receiving a powerup from the villains to evolve into Beelzebumon. He initially opposes the heroes, but has a Heel-Face Turn later, becoming The Atoner. In Digimon Xros Wars a different Beelzebumon, under the alias "Baalmon", also starts off working for the baddies, but it's really just so he can investigate who drove him to kill his comrades. He gets killed once he found out, but upon reincarnating, becomes a major player in the Xros Heart army.
In the original Sailor Moon manga, two of the Quirky Miniboss Squads (the Phantom Sisters and the Amazon Trio) get expanded roles, and are made more sympathetic than their original manga selves, eventually turning against the villains. The main single member to make the biggest change is Koan, the first of the Phantom Sisters to turn good in the television series. She was less evil and more a Love Martyr to her boss and soon convinced it wasn't worth it. Hard to believe the manga version posed as a fortune teller, convinced people they were about to die, got them to join the Black Moon Clan, but once the victim took the crescent moon mark, they would spontaneously combust. She was dealt with and forgotten like any other Monster of the Week.
The first season of the anime is a prime example with at least one of Queen Beryl's four generals, Nephrite, who in the anime falls in love with Sailor Moon's friend Naru and dies trying to protect her from his fellow generals (an event that does not occur in the manga).
Pokémon: In Best Wishes 2 Episode N, N is far more heroic than he is in thegames, going from a rival that was manipulated by Ghetsis who has his own agenda from Team Plasma to an ally of Ash and his friends and actively trying to stop Team Plasma.
Technically a case of "Dub Induced Heroism", but in the original Japanese version of Pokémon: The First Movie, Mew is a cruel, Holier Than ThouFantastic Racist who wants to murder Mewtwo literally just for being a clone. In the english dub, however, Mew is portrayed as pretty much the Big Good, trying to reason with Mewtwo and holding no true ill will towards him or his clones.
Pokémon Special does this in adapting Silver for the Gold and Silver arc. While both versions are a rival, Silver in Pokémon Gold and Silver is an all around nasty piece of work that steals his starter Pokémon and treats everyone he meets with animosity. In the manga, Silver initially displays these characteristics, but is forced to work together with Gold especially when they're captured by the Masked Man later on. Giovanni in the Red and Blue arc also acts in a polite manner towards Red that would be completely alien to his video game counterpart.
This dissonance is actually part of the main plot: Mahiro obviously has feelings for Nyarko, but has an extremely hard time reconciling those feelings with his knowledge of the Cthulhu Mythos, which has him worried that she's lying about loving him so she can destroy him and laugh at his pain, like the literary Nyarlathotep would do. In turn, this causes Nyarko to do everything in her power to prove that her love for him is honest and heartfelt; it's slow going, but it's gradually working.
In the Aku no Hana anime, Saeki seems to accept Takao's decision to break up with her with quiet dignity, and then leaves him alone. In the original manga, this instead causes her to become a full-on Yandere and eventually rape him.
Nao starts out as an enemy of the main heroes as a member of the Ori-Hime unit, then switches sides to becoming a reluctant ally, instead of starting out as a rival, then becoming a reluctant ally, then becoming a villain and only joining the heroes at the end like she does in the anime.
In the Mai Otome manga, this can be applied to the entire nation of Artai. While Nagi, the archduke, is quite the Jerkass, he never becomes the enemy of the main characters and dies saving Mashiro from the real Big Bad. As a result of this, and the fact that Sergay is a completely different character here (which means she doesn't have her feelings for him come into play), Nina also stays on the heroes' side for the entire story.
The villianess Silver Banshee was turned into a troubled but clearly heroic young woman in the New 52Supergirl stories whose first appearance has her jumping in front of Kara to stop soldiers shooting her. Later issues have hinted that she's having trouble keeping her superpowers (inherited from him evil father) under control but even here the implication is she is heading towards being a Tragic Villain rather than the totally unsympathetic character she used to be.
And, she's now staying Supergirl's BFF. For now.
Terra, who had been previously a Sixth Ranger Traitor, and dead, has been a heroine and standing member of the Ravagers.
Arthur Light, better known as Dr. Light, was a third-string baddie and punching bag of the Teen Titans (who had a rape retconned into his backstory in an attempt to make him more evil) pre-New 52. Now he's a supporting member of the Justice League of America and he died a hero.
Batman: Zero Year follows the Dark Knight Trilogy portraysl of Commissioner Loeb as incompetent but well-meaning, rather than corrupt.
In Noob, Gaea negotiated for her guildmate's (except Omega Zell) immunity from Tenshirock's "attacks" as part of her frequent cooperation with him. The webseries and novel storylines have that immunity be Tenshirock's personal initiative while the nicest things Gaea ever said or did fell into Jerk with a Heart of Jerk.
In Marvel Comics, Circe (as in the evil sorceress who turned Odysseus' men into swine in The Odyssey) is the heroine Sersei, one of the Eternals of Earth and occasionally one of The Avengers. (In her backstory, it was clear that Homer distorted the facts quite a bit; yeah, she turned them into pigs, but to make a long story short, they started it.)
In Ultimate X-Men, Pyro was a Morlock who supported Xavier's dream and later joined Bishop's X-Men, rather than a member of the Brotherhood. (He apparently underwent a completely unexplained Face-Heel Turn prior to Ultimatum, but then the details of how his powers changed as well, so maybe it was a different Pyro...)
Kin in Teenage Jinchuriki Shinobi starts off as a minor villainess like her canon counterpart, but was given a shot at redeeming herself after having a small talk with Splinter of how Orochimaru basically used her her entire life, while she dies in canon.
Films — Animated
A few protagonists in Disney Animated Canon are adapted this way to be more approachable to audiences. While still the heroes in most of the original novels, they are often far more abrasive and self serving, often due to Values Dissonance. Pinocchio for example was altered from a Bratty Half-Pint to a more innocent and merely easily misguided Cheerful Child. Likewise, Aladdin is a great deal more ruthless and unscrupulous in the original tale.
Also, many an adaptation created after that storyline will have Black Widow look like a traitor but prove to be very much on the level, and needing the other Avengers to not know what she's up to just yet.
Films — Live-Action
Judah Ben Hur from Ben Hur. In the novel, the plot is kicked off when Judah accidentally knocks a roof tile on the head of a Roman centurion and gets arrested. In the movie, Judah's sister is the one who dislodges the roof tile, but Judah deliberately takes the blame in an attempt to spare his sister. In the novel, when Judah is on a sinking slave ship, and finds himself unchained, he gets the hell off the ship. In the movie, Judah takes the opportunity to punch out a guard, steal his keys, and free all the other slaves on the ship, before escaping himself.
In Daredevil, Elektra wants to avenge her father's death by killing Daredevil, whom she faslely believes to be his killer, and the worst thing she does is to attack Daredevil under false pretenses. In the comics, she's a contract assassin who killed people for kicks while in college, and once belonged to an evil cult of ninjas known as the Hand.
In the 1982 film of Evil Under the Sun, Mrs Castle, originally nothing more than the rather strict hotel owner, is given the name Daphne and combined with the character of Rosamund, becoming Kenneth's love interest and Poirot's main assistant during the investigation. She also helps him trap the killer at the end by taking his signature.
Happens inadvertently to Narcissa Malfoy. The films keep her worrying for her son's life and betraying Voldemort at the end but leave out scenes showing her haughty racism and general Rich Bitch attitude before her Heel-Face Turn.
Also happens to Rufus Scrimgeour. Though never a villain, in books six and seven he's treated as something of an opportunistic antagonist who really only wants to work with Harry to make himself look good. In the film series he's introduced briefly in the seventh movie, where he cryptically tells Harry and the gang that he doesn't know what they're up to, but that they can't fight Voldemort alone. And then he dies off-screen.
Several film adaptions of The Hunchback of Notre Dame, most blatantly the Disney movie, apply this trope to the principal characters (Quasimodo, Esmerelda, and sometimes Phoebus) and invert it with Claude Frollo (omitting his capacity for compassion and creating selfish motives for his initial actions). In the 1923 version, however, this trope is played straight with Claude, whose evil side is given instead to his brother Jehan.
Ironically two of Julie Andrews most famous roles were the result of this:
Mary Poppins is much stricter and sterner in the original novels. The film makes her more of a Sugar and Ice Personality, to the degree that the original author thought she was too nice.
Maria Von Trapp appears in The Sound of Music to fulfil a Manic Pixie Dream Girl role. In reality she was the stricter parent. The real Von Trapp children were disturbed by how their father was portrayed and asked producers to soften him a bit.
In the 1982 film adaptation of Ivanhoe, Sir Brian died heroically. Though he could easily have defeated Ivanhoe, who was fighting as Rebecca's champion, he let himself be struck down for Rebecca's sake.
In Prince Caspian, Queen Prunaprismia is stated to have disliked Caspian and wholeheartedly supports her evil husband Miraz. In the film, however, Prunaprismia is portrayed in a more positive light. She shows sympathy for Caspian, and she expresses horror at the fact that Miraz murdered his brother. (The BBC adaptation, on the other hand, increases her villainy by depicting her as a harpy who shows open hostility towards Caspian.)
Jason and the Argonauts has Jason as a Designated Hero who travels all the way to Colchis to rob Aeetes's Golden Fleece because he wants his kingdom back. The Hallmark version of the film changes this as Jason must get the Fleece or else Pelias will kill his mother. Medea gets this as well in both film versions. In the original she was a Manipulative Bitch who made Jason promise to marry her in exchange for her help and she killed Pelias herself when Jason decided not to accept the kingdom. In the Hallmark film she is shown to genuinely love Jason and grieve for the deaths of her brother and father.
The film version of Kick-Ass makes both Big Daddy and Red Mist much more sympathetic than in the original comic. Film Big Daddy is profoundly messed up but very much a Tragic Hero, whereas in the source material his apparent backstory was just a lie and he's actually a vigilante in it for kicks. The film version of Red Mist strips him of his Dirty Coward personality from the comic and plays up his lonelieness, and the sequel is confirmed to continue in this manner.
Ditto for Eponine. First of all in the novel she bullied Cosette along with her rotten parents. In the film she is only briefly seen as a child and doesn't interact with Cosette. As an adult in the novel she is incredibly bitter over her situation and jealous over Marius's love for Cosette. The film makes her more sympathetic as she comes across as merely broken-hearted that Marius does not love her. Hiding Cosette's letter to him comes across as a heat of the moment act of despair rather than an actual attempt to sabotage their relationship. Also in the film she screams to alert Cosette and Valjean that her parents are outside the house while in the novel she only threatened to do so, making her come across more heroic.
The Mask itself. In the comicbooks it is deliberately malevolent and corrupting and compels its wearers to commit atrocity after atrocity with the immense power it gives them, before they die and it goes to its next "master". In the film it makes them harmless tricksters for the most part (though Stanley does rob the bank he works in) and only amplifies the wicked nature of already evil wearers.
The same can be said for Stanley Ipkiss. In the film he's a loveable loser with a lot of nevertheless redeeming qualities who ultimately learns to stop relying on The Mask to solve his problems, rises to the occasion, and gets the girl. In the comics he's a right-wing lunatic who uses The Mask as his personal hitman to kill those who wronged him for increasingly trivial reasons (such as suffocating his elementary school teacher), goes on a violent rampage against the police, and is ultimately shot and killed by his girlfriend.
In the novel of Matilda Hortensia bullies Matilda and Lavender. In the film she is friendly and protective of them.
The 1991 remake of The Night of the Hunter has the kids' father murdered in his cell by the Big Bad rather than hanged for a bank robbery gone wrong, making it possible that it didn't go as wrong as in the original book and movie (i.e., that the father has no blood on his hands).
In Silent Hill, Dahlia Gillespie, who was one of the major villains in the first game, plays a minor role as a member of the religious cult led by Christabella, who, unlike Dahlia in the original game, genuinelly loved Alessa and felt guilty for her suffering.
The original story of The Scarlet Pimpernel has Marguarite send the Marquis to his death in revenge for his attack on her brother; the 1982 film adaption has her innocent of this crime, framed by Chauvelin instead (for whom this trope is inverted).
In Spider-Man 2, Doctor Octopus is rewritten a good man turned into a monster by an accident, and he earns redemption in the films' climax. The Green Goblin is less sympathetic, but gets a dying moment of decency that would be utterly foreign to the comic-book version of Norman Osborn.
The Sandman is similarly softened in Spider-Man 3, but this may simply be an adaptation of his heroic, reformed characterization in the 1980s and 1990s. In the comics he makes a Heel-Face Turn, but in the movie, he only ever stole to get the money needed to save his Ill Girl daughter, and departs on good terms with the hero after telling his story. This is... not how their early encounters went in the comics.
In Alfred Hitchcock's film version of Strangers on a Train, Guy changed from a tragic demoralized anti-hero to an unambiguous hero, who did not succumb to Bruno's pressure to murder his father.
The movie Switch! is an unofficial remake of Goodbye Charlie. In both an unapologeticly sexist male Casanova is shot dead and reincarnated as a beautiful woman but in the older film he/she is firmly in Unsympathetic Comedy Protagonist territory. In the newer film the reincarnated hero/ine is a much more likable character, actually learns a lesson or two and ends the film on a someone happy note.
The Tekken film changes Heihachi Mishima from a Corrupt Corporate Executive to a much more sympathetic character who is revealed to have saved Jun Kazama from Kazuya.
In Terrence Malick's The Thin Red Line Witt is a wise, kind character and a Messianic Archetype; in the book the film is based on, he's racist, volatile and no better or worse than the rest of C-for-Charlie.
Happens in the film adaptation of Eclipse. Remember the infamous "rape-kiss" between Jacob and Bella? In the book, Bella's boyfriend Edward doesn't make much of a fuss over it, her dad Charlie approves of Jacob's actions, and Jacob himself is a Jerkass over the whole thing. In the adaptation, Edward is furious with Jacob, Charlie is shocked when he finds out about it and Jacob acknowledges that what he did was wrong.
Harada in The Wolverine, sort of. In addition to pulling a Heroic Sacrifice to save Logan, he's far less of a Jerkass than his comic counterpart, who is a foreigner-hating bigot.
Captain von Schoenvorts is a thoughtful U-Boat officer who treats his men fairly, forbids the killing of survivors after sinking the British ship, and works loyally and faithfully alongside Tyler and Bradley in Caprona, and who ultimately dies tragically thanks to the betrayal of his treacherous second in command Dietz. This is in direct contrast to the novel where Baron von Schoenvorts whips his own men for minor offenses, intentionally has the U-Boat fire on survivors of the ship they sank, betrays the British crew in Caprona and uses them as slave labor, and dies as a result of some severeLaser-Guided Karma.
A more minor example is Benson. In the film, he's just one of the British crew and a definite good guy who gets killed in a fight with some Sto-Lu warriors. In the novel, he is a traitor helping the Germans, and dies aboard the U-Boat long before the characters even get to Caprona.
The Union from Cloud Atlas is portrayed as an actual rebellion. Contrast to the book in which its just staged by Unanimity so that they can distract the people from the actual problems going on in the government.
Timothy Cavendish is given this too, seeing how his more racist and misogynistic aspects of his personality aren't even brought up in the film.
In The Talented Mr Ripley, although Tom Ripley commits the same murders as he does in the book, he is presented as much more emotional and caring, with his sociopathy significantly toned down. As a particular example, Ripley in the books is introduced pretending to be an official with the electric company/other creditor organizations, and calls random people up to pressure them about (nonexistent) bills, partly so he can support himself on their money and partly for his own amusement. In contrast, Ripley in the film works as a waiter and engages in relatively innocent deceptions in which he lies about his background. He also benefits from he fact that Dickie, his first victim, gets a considerable dose of Adaptational Villainy, going from an Upper-Class Twit in the book to a caddish borderline sociopath in the film.
In Myth-O-Mania, mostly with the help of Hades, encounters with famous monsters from Classical Mythology tend to be resolved peacefully, and many of them are friendly and misunderstood rather than evil. The Hydra becomes one of Hercules's True Companions, and killed humans with her poisonous breath by accident rather than malice. The Minotaur is a perfectly decent vegetarian whose human "sacrifices" are found alive and well, intended as wrestling partners instead of food, while the Calydonian Boar is a down-on-his-luck wrestler who just wants his job back.
The Worst Witch did this with a lot of characters who mostly made one or two appearances in the books but had their roles expanded on the series.
Miss Drill was a strict Drill Sergeant Nasty who becomes the teacher the girls can confide in the most.
Miss Bat similarly was your average strict teacher as well but got changed to a quirky and lovable Cloud Cuckoo Lander that was always friendly to the girls.
Ethel herself gets a few Hidden Depths and becomes a sort of friend to Mildred in the spin-off Weirdsister College.
Miss Hardbroom was a Sadist Teacher that got maybe one Pet the Dog moment in the books. She is still a bit of a Sadist Teacher in the series but is much more sympathetic and is shown to genuinely care for the girls and the welfare of the school.
Sherlock exploits and this in the form of Dr. Stapleton, who shares the name of the villain of the novel "The Hound of the Baskervilles''. The culprit turns out to be a completely different character.
Power Rangers Samurai does this in adapting Samurai Sentai Shinkenger's Fuwa Juzo into Deker. Both of them are Blood Knights, but while Juzo is a remorseless killer, Deker was made into an Anti-Villain by making his battle-lust a curse placed on him that he hates. Basically, Deker is what Juzo led us to think he was before The Reveal that he wasn't misunderstood, just evil. However, this makes Deker's death in a manner similar to Juzo'sever so tragic.
Dayu is made more sympathetic, especially back during her human days, even if in the end she does just as much bad stuff in both versions.
In Tensou Sentai Goseiger, Gosei Knight is largely indifferent to helping humans, only incidentally helping them because of his mission protecting the planet itself; and often doesn't care if they get hurt in fights. In Power Rangers Megaforce, Robo Knight is exactly the same, but stops short of destroying a factory to stop its pollution as a way of protecting the environment.
Several characters in Game of Thrones are presented as more sympathetic than they are in the books.
Cersei Lannister gets several scenes in season 1 that underlines her miserable marriage to Robert, her sympathy for Bran Stark's injury (that she caused), and scenes showing her main virtue (love for her family, save Tyrion). Two of her biggest Kick the Dog moments from the second book are done by Joffrey instead.
Tyrion is an interesting example. Although he clearly is one of the better-hearted people in the books, he's still very much a Lannister and tends to be an Anti-Hero or Anti-Villain depending on your mileage. The TV show makes him into a more traditional hero by removing his more questionable decisions. For instance, it's not mentioned that Tyrion also participated in the gang-rape of his wife Tysha, and so far he hasn't ordered any loose-lipped singers added to the local soup kitchen's bowls of brown.
While much of Margaery Tyrell's apparent kindness is still an act to gain her favor with the people and the other characters, Show!Margaery seems to be genuinely fond of Sansa Stark. In the books, she only befriended Sansa as part of a ploy to marry her to one of her brothers, thereby gaining House Tyrell control of the north through her children, and shunned her when this plan fell through. While the Tyrells still attempt this in the show, Margaery remains supportive and comforting to Sansa even after she is instead married to Tyrion Lannister. This is because Garlan Tyrell, the character who played this role in the books, was Adapted Out.
In Kamen Rider Dragon Knight, some Riders are considerably nicer than their original Kamen Rider Ryuki counterparts. Ryuki is basically Highlander as a Toku, so the main hero is the only one at first who is not just out for himself. In Dragon Knight, a lot of them remain just out for themselves, but Wing Knight (Knight) and Siren (Femme) are true heroes. When Len is training Kit early on, that's taken from a scene where Ren was trying to kill Shinji because he'd be trouble down the road. Kase fighting JTC is still Kase fighting JTC, but in Ryuki, the reason is different: Miho just wanted revenge on Asakura. Also, Mirror Kit is Adam, downgraded from evil like mirror Shinji to merely selfish and eventually making a Heel-Face Turn.
In The Dresden Files books, Bianca is a high-ranking villainous vampire. In the show, she's much more sympathetic and she and Harry end up on the same side more often than not.
Shado in the original comics was a Japanese assassin who raped Green Arrow. In the show, she's a lawyer and one of Ollie's allies on the island.
Anatoli Knyazev aka KGBeast. In the comics, he was usually a Psycho for Hire, while on the show he's a sympathetic mobster who helps Ollie during his trip to Russia.
Arguably Merlyn, to an extent. In the comics, Merlyn is a Psycho for Hire and has opposed the JLA as a member of the League of Assasins and the Injustice League, while on the show, Malcolm Merlyn is a Well-Intentioned Extremist who wants to destroy the Glades to avenge his murdered wife. He's still the Big Bad and a pretty horrible human being, but is at least given somewhat sympathetic motivations.
In the Discworld novel Wintersmith, the Summer Lady is callous and uncaring, and it's made very clear that eternal summer would have been just as bad as eternal winter; it's just not what happened. The song "The Summer Lady" in the Steeleye SpanConcept AlbumWintersmith is about how wonderful she is for ending the cold. (Although the earlier "Fire and Ice" correctly portrays both the Summer Lady and the wintersmith as neither good nor evil, just balanced.)
A radio series called The Adventures of Harry Lime (in the U.K.)/The Lives of Harry Lime (in the U.S.) was created as a spin-off of The Third Man, and turned Harry Lime, an amoral, manipulative sociopath into a Lovable RogueHonest John type, with the slight justification that the series was a prequel. Also a case of/testament to Misaimed Fandom, since The Third Man presents Lime as a monstrous figure who hides his total lack of scruples beneath a lovable facade.
Agatha Christie's theatrical adaption of her novel And Then There Were None has two of the ten characters innocent of the crimes of which they were accused, survive, and fall in love. Ironically these were the two whom the murderer considered the most guilty in the original novel, and therefore saved them till last. Most film adaptations use this revised ending, although for adaptations where Lombard is replaced by Charles Morley, this trope only applies to Vera, as Lombard was still guilty and committed suicide before the start of the story.
Herbert West in his original canon? A dangerous Mad Scientist obsessed with reanimating dead bodies. Herbert West in Shoggoth On The Roof? A dangerous Mad Scientist obsessed with reanimating dead bodies... to provide humanity with the necessary immortality to combat Eldritch Abominations, with his devoted young wife by his side. He actually winds up the hero of the whole musical because of this.
He also seems to have figured out how to make sure they don't come back wrong by the end of the story, unlike in the original novella.
Like in its film adaptation (see above), Eponine is considerably more sympathetic (and saner) than she is in the original novel.
Although both are good guys in the original novel, Marius and Valjean get this in terms of their relationship. In the original novel, Valjean hates Marius (up until he- Valjean- is on his deathbed) and only saves his life at the barricades because Cosette would want it/its the right thing to do. In the musical, however, Valjean likes Marius, speaking of him as being like the son he never had. For his part, Marius in the novel hates Valjean (again, up until Valjean's death) and after marrying Cosette, prevents Valjean from seeing her in a deliberately cruel way. In contrast, in the musical, it is with extreme reluctance that he agrees to Valjean's desire to give Cosette a better life by separating from her.
Jean Racine's play "Phčdre" has Phaedra being a love martyr and trying to fight her forbidden love for her stepson Hippolytus. Unlike the antic myth and previous adaptations, she doesn't accuse Hippolyte of having raped her to her husband Theseus but her nurse does to save her reputation. She kills herself after Hyppolyte's death and reveals his innocence in her last breath.
In Mobile Suit Victory Gundam, Fonse Kagatie manipulates Queen Maria and decides to build the Angel Halo to subjugate mankind. During a Space Route scenario of Shin Super Robot Wars, Londo Bell rescues Fonse from imprisonment. He relates how the alien attack and Tassilo Vago's treachery brought about the end of the Zanscare Empire (just as Lupe Cineau had said), ending in Tassilo bringing him here a prisoner. When the party tells him that Zanscare is still active, Fonse realizes that Char Aznable must have taken control. Increasingly panicked, he tells the party they must stop Char before he achieves his misguided goal of robbing all mankind of its emotions, creating obedient soldiers as the aliens want.
In Super Robot Wars Destiny, much of Char's Neo Zeon and Gundam Wing's antagonists play the part of heroes, fighting against Zanscare and various alien threats. The most notable example is probably Treize Khushrenda, who at the end of the game sacrifices himself to seal away the Eldritch AbominationBig Bad. Of course, many other games allow you to recruit antagonists of all shapes and sizes to your cause. UX includes Ryofu Tallgeese and Master Therion, to name a pair of standouts.
Super Robot Wars GC: Zeon deploys the Apsalus III during its second attempt to capture Jaburo. Aina is piloting it but Ginias soon assumes control over it after removing a half-hearted Aina from the cockpit. Ginias asked Norris to take Aina to safety while he pilots the Apsalas III himself in spite of his poor health, vowing victory for Zeon. In essence, Banpresto treated Ginias a lot better in GC than in the original series.
In Dead Rising 2's Off the Record spinoff game, Raymond Sullivan goes from the Big Bad (one of two, at least) to a genuinely heroic person. Conversely, Stacey takes his position as the Big Bad instead.
In the The Lizzie Bennet Diaries, Lydia Bennet is developed into a much more rounded and sympathetic character than she was in the original book. Whereas the Lydia from the book was a shallow, self-absorbed BrattyHormone AddledTeenage Daughter who never even realized how much grief she had put her family through, the Lydia in this web series is shown to have a Freudian Excuse for her attention-seeking behavior, genuinely love her sisters, and be consoled by them after George Wickham takes advantage of her trust in him.
In Vaguely Recalling Jo Jo, J. Geil genuinely cares for Enya and Dio is a good father for Giorno. Also, Dio cares about his minions, as they're alive in later episodes.
While not an "adaptation" of The Jungle Book per se, TaleSpin does this to some of its reinvented characters from the Disney film. In the latter Shere Khan, while Affably Evil, was a genuine force of evil and took sadistic pleasure in the idea of killing a man cub. In Tale Spin he is still sinister, but a business man of neutral alliance, interested only in power and having a strong moral code (even siding with Baloo if someone risks offending it). Meanwhile King Louie is altered from a wily troublemaker to Baloo's best friend.
Similarly, Thomas the Tank Engine in The Railway Series, while still sympathetic, was much more of a self absorbed Bratty Half-Pint. While the show kept up this depiction for most episodes adapted from the books, its turn to original stories slowly made Thomas more altruistic and innocent. Some other engines such as Henry and Sir Handel took a similar direction.
The 1990s Spider-Man: The Animated Series actually rewrote Kraven the Hunter and Calypso entirely, with both becoming heroes once Spider-Man resolved the issues with their Psycho Serum-derived powers. (Kraven softens some and eventually makes a Heel-Face Turn, but Calypso is totally overhauled; from an evil sorceress to a friendly scientist who is only villainous in onePsycho Serum-involving episode.) Similarly, minor villain the Spot was recast as a Punch Clock Villain whose episode shows him going through a Heel-Face Turn after committing a few ill-advised bank robberies. The comics version, by contrast, is an unrepentant petty criminal with a sideline in contract killing.
In X-Men,Magneto. Mags has always been a complex character, doing acts others consider villainy or heroism as needed to protect mutants, so the sight of him helping the X-Men and meaning it is not too surprising in any continuity. However, when he's bad, look out. His list of villainous exploits is impressive, and everyone's leery of him even when he's been playing nice for a while because they know that "what must be done to protect mutants" being helping old ladies cross the street now doesn't mean it won't be "showdown that could well start World War III" someday. In this series, he's only properly villainous in his introductory two-parter, and every appearance after that has him alongside the X-Men against common foes. However, when the show came out, comic Mags had been 95% reformed for about a decade or so.
Garfield, while remaining largely the same character in all medias, is hit with this to some extent. The comic strips usually revolve around quick gags involving Garfield's snarkiness or cruel sense of humor. The Animated Adaptations however, likely due to their longer more depthful stories, keep most of Garfield's nastier qualities but also more frequently show his redeeming side, leaning him more into a Jerk with a Heart of Gold. This is especially prominant in The Garfield Show where he is occasionally toned down to the point of being outright altruistic.
One episode of DuckTales had a gruff but outright heroic Pete who was only positioned as a potential villain as a Red Herring.
In the Marvel Comics universe, Berzerker was a minor villain and member of the Morlocks. In X-Men: Evolution, he's a teenager and member of the X-Men.
The Morlocks in general. In the comics, they're in the Heel-Face Revolving Door; their suffering from their odd appearances or Blessed with Suck powers is real, but attacking humans to punish them for it is Not Cool. Sometimes they get better, and sometimes they get Aesop Amnesia. The Evolution version is not known to attack humans unprovoked, and the 90s 'toon version starts out villainous but cuts it out when Storm takes over, and there's no revolving door.
In the comics, Mongul is an Evil Overlord with no real motivation other than being a sadistic bully and general douchebag. In the show, he's still definitely a dick, but his extreme hatred of the Reach and desire to eradicate them makes him a fair bit more sympathetic.
In Superboy comics Dr Amanda Spence is an Evilutionary Biologist who created Match, and killed Conner's girlfriend Tanya Moon For the Evulz. In the series, Conner accuses her of creating Match but it turns out this is unfounded, and she later helps create the anti-Starro technology.
Finally, there's Vandal Savage. In the comics, he's probably the single most thoroughly vile individual in the DCU with many thousands of years worth of absolutely horrific crimes to his name. In the show, he's still definitely not a nice guy, but he's a Knight Templar visionary whose acts are motivated by a desire to drive humanity to advance and make Earth a major universal power.
Rumaan Harjavti is depicted as a benevolent figure and the democratically elected president of Qurac. In the comics, he was the Bialyan Queen Bee's predecessor as the ruler of Bialya and like her was a foe of the Justice League, though he was less intelligent.
Major Force may be a subversion. In the comics he's a violently sociopathic and blood-thirsty villain. In the comic tie-in to the show he's a hero sponsored by the government, whom the Justice League want to recruit. The reason he's not on the league is because Captain Atom shoots his suggestion down because of history he has with Force, his dialogue implying that Force isn't as heroic as he seems.
From Teen Titans, we have Terra. In the comics, Terra horrified even Slade with her ruthlessness and manipulative sociopathy. This Terra, however, is a Broken Bird who was Driven to Villainy by a desperate need to live a normal life and performs a Heel-Face Turn after some convincing by Beast Boy.
Plasmus can't control his transformations into a mindless monster and willingly submits to being kept in stasis for most of his life. In the comics, he is in full control of himself and likes melting people.
In Wolverine and the X-Men, Nitro releases giant explosions of energy whenever he's stressed, or just when enough energy is stored up. Like Plasmus above, he submits to confinement so he doesn't harm others, and is used by the villains as a blunt instrument against his will. In the comics, he's a killer for hire, and caused both the death of the Kree Captain Marvel and the Stamford Incident that killed about 700-ish people. (Interestingly, there was a one-shot child character in Uncanny X-Men who was like the animated Nitro but more adorable.)
The Beware the Batman versions of Professor Pyg and Mr. Toad fall under this. While the comic version of Pyg is an insane freak who murders and mutilates people at random (with Toad being simply his lackey), the cartoon reinvents him as a dapper, sophisticated villain with a Victorian-era flair. Instead of being a serial killer or performing medical experiments on people, he and Toad are eco-terrorists who specifically target rich businessmen whose careless activities have harmed animals or the environment. That said, what they do with said businessmen is still pretty sick (hunting them down and killing them like animals), and Pyg himself still wields surgical equipment that he's all too eager to use.