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.
Shadi in the manga and first anime is a Manipulative Bastard who has absolutely zero problem using innocent people as pawns. The version in the second anime has much more of a sense of honor and helps Yugi and his friends out more often. Not to mention that the two Millennium Items he had - the Key and the Scales - had the potential to be the most dangerous of them all. The Key allowed him to enter a person's mind and reconfigure the victim's personality any way he desired (making the victim his slave if he had to) while the Scales seemed to be a representation of the Scales of Maat, and could judge a sinner and not only kill him if his guilt was confirmed, but possibly condemn his soul. (Indeed, it's likely a good thing he held onto both of them.)
In the Yu-Gi-Oh! GX manga, Ryo/Zane is far less of an Aloof Big Brother to Sho/Syrus, and doesn't view him as untalented as much as being too concerned with his opponents' feelings to win (for example, throwing a duel because his opponent was getting upset). He also never becomes Hell Kaiser, and is on the heroes' side the entire time.
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 ˝ 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.
Unique to the anime, the first season villain Nephrite (one of Queen Beryl's four generals) falls in love with Sailor Moon's friend Naru and dies trying to protect her from his fellow generals.
Also in the first season, the Brainwashed and Crazy Endymion acts as a Noble Demon who often comes into conflict with Kunzite's questionable tactics, so much that he teams up with the Sailor Senshi almost as much as he did before his brainwashing, whereas in the manga, Endymion became a full blown Card-Carrying Villain.
Sailor Moon R has Quirky Miniboss Squad the Four Phantom Sisters (who's roles are expanded with sympathetic backstory) performing a Face-Heel Turn against the Black Moon Clan and committing to normal human lives. Youngest Phantom Sister Koan, the first to turn good, was a Love Martyr to her boss and soon convinced it wasn't worth it. The manga version posed as a fortune teller, and convinced people they were about to die to get them to join the Black Moon Clan, only to cause converts to spontaneously combust. She was killed and forgotten like any other Monster of the Week.
Sailor Moon SuperS has Quirky Miniboss Squad the Amazon Trio, who instead of being one shot Monsters of the Week, have existential crises over their lack of dream mirrors and animal natures and befriend the heroes before reverting to animal shapes and being taken to a magical sanctuary.
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 alongside Team Plasma to an ally of Ash and his friends and actively trying to stop Team Plasma.
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.
He was an example of the trope from the start. While both versions of the character stole their starter, the games' Silver did it for his own selfish purposes, whereas his Special counterpart did it so that it would help him in his mission to stop Masked Man.
The series serves to hang a massive Lampshade on the concept, since the Cthulhu Mythos exists In-Universe. The protagonist Mahiro and his mother Yoriko are both Lovecraft fans, and as such expect the worst when they first learn they're dealing with beings like Nyarlathotep and Cthuguha. However, over time they warm up to the alien characters after realizing that they're only vaguely like their literary counterparts and are on the whole good people.
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 anime makes Mitsuru's character much less offensive, by essentially making him Misaki's private Paparazzi, who only takes pictures of her when she's out in public. Which is also made humorous, since he often happens to catch her in various states of undress, thanks to Kadotake's clumsiness. When he isn't following her around, he acts as one of her contacts and even helps her save Ai, near the climax of the second episode.
In Pokémon Anime, Damian is an Jerkass trainer who abuses and abandons his Charmander, which Ash adopts. However, in several adaptations he is more sympathetic. In The Electric Tale of Pikachu, he actually meant to return to get Charmander and shows concern for it, but was injured in an accident. He even goes to look for Charmander later himself, before he completely recovered, and is later happily reunited with it. In Pokemon Yellow, he admits that he is a poor trainer and gives Charmander to the player in hopes that they can do a better job than him.
In the Danganronpa anime, Byakuya Togami is still quite a jerk who is callous and doesn't think much of cooperation, as he was in the visual novel. In the anime, however, he doesn't openly profess that he's planning to eventually murder someone and get away with it.
In the Bokurano manga, Chizu, while tying to get revenge on the men who gang-raped her, fires Zearth's lasers at them and feels no remorse for the many innocent people who are caught in the blasts and killed. She just barely is talked down from killing Hatagai, her teacher, former lover and final rapist by her sister, who tells her to kill her as well, and her family, after learning what she did and what was done to her, considers her actions all but unforgivable. In the anime, she doesn't kill anyone prior to her aborted attempt on Hatagai's life, which she stops the moment that she sees her sister try to protect him. On a more debatable sense, in the manga, she kills Kako, while he's beating up Kirie, but in the anime, she pushes him away when he tries to rape her, causing him to fall down the stairs and die when the building he's in collapses.
Akise Aru in Mirai Nikki is never portrayed as a villain in either the anime or the manga, but gets a small, but extremely important change between the two. In the anime, when Yukiteru snaps upon learning that he wouldn't be able to bring the people he'd killed back to life even if he won the game and guns down his remaining friends, Akise tries to stop him. In the manga, the scene is almost the same, except Akise hangs out off panel and just watches him do it, feeling that he didn't need anyone else and that they were just in the way, in essence outing himself as just as much a Yandere as Yuno.
In the Wedding Peach manga, Pluie was a loyal demon to the end and died when he tried to take Momoko with him by tackling her into a demon vortex. In the anime, he was nice enough to throw Momoko her ring back as he fell in, and didn't actively try to make her fall in.
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 her 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 portray of Commissioner Loeb as incompetent but well-meaning, rather than corrupt.
After saving the wrld during the Forever Evil event, Lex Luthor and Captain Cold are now part of the Justice League.
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...)
In a meta sense, it was: A new writer didn't know about Ultimate Pyro's portrayal and basically made him the main universe Pyro in terms of personality and powers.
The Archie Mega Man comics do this with the Robot Masters from the original game, with Mega Man's attempts to talk them out of following Wily's orders convinces them to help him, and later join and serve his supporting cast when Wily's programing to them is undone.
Mad Madame Mim from Disney's The Sword in the Stone was a genuinely villainous character who tried to kill Arthur because, as she made no effort in hiding, she's evil. In the Disney comics that later featured her, she was more of a harmless witch or occasionally even a heroic one.
Gilda gets this treatment a lot. It helps that while she was a jerk, she was only a jerk, and she was non-horrible enough to have been Rainbow Dash's friend for some time pre-series. If Big Bads like Discord and Sunset Shimmer can be Easily Forgiven it seems almost petty to hold mere rudeness against Gilda.
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.
Jason Todd in Young Justice Darkness Falls. Remember how the original Jason Todd went Jumping Off the Slippery Slope after his resurrection? Well in this fic, Jason, while still not a good guy in the same way The Team and the League are, still stands to fight The Light and use his gang to fight criminals. The fact that he was injured disarming a bomb of Two-Face's rather than getting beaten to death by The Joker might have also helped. In fact, this fic actually has Jason and Bruce reconcile and come to an understanding at least.
In The Prayer Warriors, Luke Castellan from the Percy Jackson series is inexplicably on the heroes' side, despite being the canonical traitor in Camp Half Blood, and Draco Malfoy is a "secret Christian" at Hogwarts. This is odd, as most of the other villains from canon are also the Prayer Warriors' enemies.
Up for debate if this is true with Godzilla in the Godzilla and My Little Pony:Friendship Is Magic crossover, The Bridge. While in most of the Toho and recent Legendary continuities he's more often just territorial animal lashing out rather than an intentional villain; he was only fully benign in the late Showa series back in the 60s and 70s. So far and according to Wordof God, this Godzilla will be heroic after some misunderstandings are straighten out. Some say it's justified as this is incarnation is the grown up Godzilla jr. from the Heisei series, who was hatched by and was generally amicable towards humans; and thus was a gentler soul smaller sentient creatures than his adoptive father.
Some characters in Kitsune no Ken: Fist of the Fox get a complete personality makeover in contrast to their original personalities in Naruto. Specific examples include Kabuto, who in this story is the benevolent retainer to the Hyuga family and a Shipper on Deck for Naruto and Hinata (in canon, he's The Dragon to Orochimaru and definitely not a trustworthy person); Uchiha Fugaku, the head of the Uchiha Zaibatsu and a caring father to Sasuke as well as a decent guy in general (canon Fugaku was emotionally distant from Sasukeand was planning to start a coup together with the rest of the Uchiha clan); and even Orochimaru, who's simply doing his job as a defense attorney in getting Mizuki's goons out on bail but is otherwise not shown to be malicious (canon Orochimaru, besides being a major antagonist for most of the series, is a Mad Scientist and Bad Boss to his own henchmen).
Necessary To Win does this with Black Forest from Girls und Panzer. It's suggested that Erika and those who also criticized Miho's decision to save her teammate are not necessarily the majority in Black Forest, but the most vocal group. There are several others who support Miho's decision, even if they're not entirely vocal about it. Maho is a minor case, as her more benevolent motivations are more openly touched upon here.
A few protagonists in 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.
The Enchantress from Beauty and the Beast is a curious example. In the original tale, she was a wicked fairy who cursed the prince for no good reason. The film has her curse the prince after he refuses her shelter and shows himself to be selfish. While not presented as a heroic character, her spell served to teach the prince about love rather than anything malicious.
Hera is presented as Hercules's loving mother. In the myths, she was not his mother and did not like him one bit - it was her that made Herc go mad and murder his wife. The film omits that plot entirely and gives Adaptational Villainy to Hades.
Anyone who knows their Greek myth knows that Zeus is kind of a womanizing jerk that puts such a high standards to everyone, but never once applying it to himself, making him a self-righteous prick. Here, he's pretty much a cross between Grandpa God and Bumbling Dad who certainly loves Hercules and stays loyal with Hera, making his status as a Top God of Mt. Olympus and Big Good of the series a lot more plausible.
Rapunzel's parents in Tangled. The father steals lettuce from a witch's garden in the original tale, simply because his pregnant wife had a craving for them. They also disappear from the story and never seem to bother about the whereabouts of the daughter they gave up. In the film, the mother is dying. And rather than knowingly stealing from the witch, they find a golden flower that the witch had been using to make herself young. And the witch kidnaps the baby. Rapunzel is also reunited with her parents at the end - and they're implied to have been searching for her all her life.
Same case in Barbie as Rapunzel. This time the witch stole Rapunzel and kept her locked up because her father didn't love her.
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.
James Gordon Jr, whom displays no signs of being the Ax-Crazy bastard he was in the comics.
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 Hercule 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.
Although Rufus Scrimgeour was 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.
In the books, Severus Snape is a Jerkass, plain and simple. In the movies, he's still unpleasant, but has a few Pet the Dog moments, such as shielding Harry, Ron and Hermione, the 3 students he despises from werewolf!Lupin, putting his own life at risk in the process.
Barty Crouch Sr. in the books is a Knight Templar implied to have a bad case of He Who Fights Monsters. He and Harry barely interact, and his neglect of his son is highly implied to be one of the reasons Barty Jr. joins Voldemort. In the film, he and Harry share a pleasant conversation shortly before his death, and he is visibly distraught about having to send his son to Azkaban.
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.
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.
Many adaptations of Pride and Prejudice do this with Mary Bennett. In the novel she is a bookworm and a bit of a Shrinking Violet - but she is also very ignorant, rude and loves to lecture people. A lot of films file off the unlikeable parts of Mary which leaves her looking more sympathetic. The 2005 film is a notable example, especially the scene where she cries into her father's arms that she practised the piano all day but couldn't perform at the ball.
Bride and Prejudice does similar things with Mrs Bennett's Expy Mrs Bakshi. While still presented as pushy and over-the-top, she gets a few Pet the Dog moments. Mr Bingley's (or Balraj now) sister also becomes much less snobby and more friendly.
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.
Kick-Ass' Love Interest Katie is a kind, compassionate young woman, whereas her comic counterpart is an absolute bitch. At least in the first film. When the sequel rolled, she Took a Level in Jerkass, closely matching her comic counterpart's personality.
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.
In fact, this softening of Eponine's character has made her one of the most popular (if not the most popular in some circles) and beloved characters in the fandom of the musical and film versions of Les Mis; after all, many people can relate to Unrequited Love and sympathize with her. In addition, Eponine is a great deal spunkier and more relatable than her book counterpart. Also, in the film, Marius and Eponine's friendship is emphasized and given importance while in the book Eponine was a bit of a Stalker with a Crush; while Marius loves and cares for her, it's only as a friend, which makes Eponine's sadness that he doesn't love her the same way she loves him all the more poignant.
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 denounce the Marquis, accidentally sending him and his family to their deaths in revenge for his attack on her brother; the 1982 film adaption has her innocent of this action, 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. Though at the very least prior to being the Green Goblin Norman was shown to be a good man if a bit of an aloof father and stressed businessman, the Goblin formula drove him insane and created a split personality. In the comics as Peter pointed out "He was a bad man turned worse"
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 The 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.
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 is portrayed as an actual rebellion. Contrast to the book in which it's 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 the novel Congo, Karen Ross is a Jerk AssCorrupt Corporate Executive who only wants to get to Zinj to get ahold of its diamond mines and causes the destruction of the site when she makes a controlled detonation during a geological survey that triggers a volcanic eruption. In the movie, she travels to Zinj in search of her Canon Foreigner boyfriend who works for the same company and disappeared during a previous expedition there, and the volcanic eruption is a coincidence.
In the sequel Captain America: The Winter Soldier there's a flashback to pre-serum Steve after his mother's funeral where Bucky tries to console him and Steve says it's alright since she's "now with dad".
The 1990 film version of Cyrano de Bergerac made Christian, the Unknown Rival to the titular character in love, more heroic and sympathetic than in the original play (though he was already an alright guy) by having him rescue his love Roxane when her attempt to charm her way through enemy lines doesn't work, unlike the play.
Speaking of Godzilla monsters; King Ghidorah is known throughout the films as Godzilla's archenemy. The Showa Era depicted him a complete villain who gleefully destroyed cities while the Heisei Era showed him as the weapon of conquerors from the future. However, the version of Millenium Era film Godzilla, Mothra, King Ghidorah: Giant Monsters All-Out Attack! is an ancient dragon who served as one of the guardian monsters of Japan, awakening to fight Godzilla to save the world, not to destroy it.
It's basically an entire film dedicated to this trope. It provides a previously unseen tragic origin for the title character, causing her to come off as much more sympathetic than she did in the original Sleeping Beauty film.
Same goes for her Dragon, Diaval, who in the original was petty and cruel. Here, his loyalty to Maleficent is highlighted and he's given more character traits and screentime, causing him to come across as a far better person.
Harada, 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.
Yukio was much more morally ambiguous in the comics (especially in earlier appearances, where she was a mercenary/assassin/thief) than in the movie.
In the comics, Quicksilver is often an outright jerk (often intentionally), in X-Men: Days of Future Past he's more of a merry mischief-maker. Overall he is still more heroic than most adaptations portray him and while he can easily make it out on his own once the breakout goes bust, he instead goes out of his way to save Logan, Charles and Magneto, even though he already broke the latter out of his prison by technicality. He also clearly is not impressed by the idea that he helped break out the person suspected of killing JFK once he finds out, and is especially shown to be horrified by Magneto's "demonstration" in the climax.
Future Cops is basically a comedic parody film of the Street Fighter where they got the alignment of some characters reversed. One of the heroes, Ti Man, played by Andy Lau, is based on Vega, who in the game proper is actually a sadistic, dangerous The Fighting Narcissist and one of the game's villains.
Kinpatsu Sakamochi was a sadistic rapist who often cracked jokes at the expense of the students that died in the Program. Kitano, his counterpart from the film, while still no saint, is shown to be more sympathetic. He often dealt with students that disrespected him and a daughter that wanted nothing to do with him. He even tried to make sure Noriko wonbecause she was the only student that showed respect for him.
Hirono Shimizu, while not evil in the novel, she wasn't very nice either. In the manga, she was open to the idea of joining Shuya's rebellion, and it was taken even further in the film where she called Mitsuko out for killing Megumi, the latter of whom she bullied in the novel.
In the novel version of the The Help, Skeeter Phelan is a segregationist who finds the thought of an interracial romance to be "horrific, disastrous." She's still a sympathetic protagonist, but she's nevertheless a somewhat ambiguous character. In the movie, by contrast, there is much less moral complexity, and Skeeter is never portrayed as a segregationist.
In almost every version of The Iliad ever put to film, the Greeks (the heroes of the poem) become the villains, and the Trojans (the villains of the poem) become the heroes. This is particularly galling in the case of Paris, who in the epic, was a sniveling, backstabbing coward, who hid inside the city and let his brother do all the fighting. But Hollywood wants a love story, and Paris' promotion to romantic lead inevitably includes a batch of good qualities that weren't present in the epic poem, and the quiet ignoring of the fact that his "love interest" was essentially roofied by a goddess. To a lesser degree it also applies to his brother Hector, who, while more conventionally heroic in the poem, was still a) willing to dismember a man's body and hang it from the walls, and b) too afraid to face Achilles in direct combat. The 2004 version, Troy also gives Achilles something of a hero upgrade, turning him from a nihilistic narcissist into a troubled, but genuine, hero.
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.
In his original portrayal Sun Wukong kills wantonly as soon as he is not within the presence of his master. This happens throughout almost the entire journey. The popular 1996 and 2002 HK adaptations had him portrayed as a more merciful character from the start. As a result, his actions of killing the robbers, hunters, and oppressors were often omitted.
Tang Sanzang's original portrayal was worse. Acts hypocritically or at best inconsistently, and seemed to treat his disciples as tools most of the time. He also wept fearfully when threatened by demons, while popular adaptations such as the HK versions (1996 and 2002) had him face death with dignity and showed genuine care and concern for his disciples.
Then again, those weren't faithful adaptations from that start.
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.
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.
Sanbash, the first general in Seijuu Sentai Gingaman, was a violent, dirty thug. His counterpart in Power Rangers Lost Galaxy, Villamax, was the polaropposite. However, he's a partial example: Sanbash's role in the story was held by Furio, who didn't look like Sanbash 'cause (it is said) the costume hadn't arrived yet. The costume did finally show up and so was used later, becoming Villamax, a character whose role in the story didn't exist in Gingaman. Furio is not a sympathetic Noble Demon.
Alex in Power Rangers Time Force. While he is still a massive Jerkass, he's ultimately well meaning and trying to save the world. His counterpart in Mirai Sentai Time Ranger, on the other hand was not only a Jerkass, but also downright evil, having been responsible for the events of the series occurring in the first place, and despite making efforts to save the future, he was willing to allow mass destruction to be wrought in the present, and part of his motive for manipulating events was to avoid a vision where he died as Time Fire by making somebody else become Time Fire and die in his place.
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.
Renly Baratheon is changed from a prideful Sleazy Politician with entitlement issues to a serious and thoughtful young man who rebels against Joffrey out of a genuine sense that he'd be better at the job. The TV character is more intelligent than his book counterpart (who dismissed books because he believed they should only be read by maesters), and Gethin Anthony has stated in this featurette that Renly is "very educated." His main Kick the Dog moment (mocking Brienne of Tarth behind her back) is changed to sincerely respecting her abilities and service.
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.
While much of Margaery Tyrell's apparent kindness is still an act to gain her favor with the people and the other characters, on the show she 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 the show she was also explicitly ignorant of her grandmother's plot to kill Joffrey, of which Sansa and Tyrion were blamed, while the book is more ambiguous but implied that she knew.
Kamen Rider Fourze's movie pulls both this trope and its opposite with characters based on Space Ironmen Kyodain, another Shotaro Ishinomori creation. Inga Blink (named after the villain Goblin Queen; in Japanese, it's an easy anagram, gaburin kuin to inga burinku.) and her bodyguard Black Knight help Fourze and friends battle the evil Kyodain siblings, older brother Groundain and younger sister Skydain (the good ones in the original series were younger brother Grounzel and the older, very malee Skyzel), though at first Inga appeared to be a villain.
The Crossover between Fourze and Kamen Rider Wizard likewise casts the Akumaizer 3 trio as villains. They get new names to distinguish them from the originals also, losing the b/v syllables in their names. It also seems to do the same to Inazuman, having a similarly-named character who turns into Sanagimannote Inazuman's pre-evolution antagonize Fourze; in the end it turns out that he's just suffering from All of the Other Reindeer and after a heart-to-heart with Fourze pulls a Heel-Face Turn, changing into Inazuman for the first time.
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.
Also, Morgan in the books, while a good guy, was a Lawful StupidInspector Javert who watched Harry like a hawk waiting for the slightest excuse to chop off his head. This version doesn't trust Harry but wants to help the innocent too, which leaves them begrudgingly on the same side more often than not, while having a problem with how visible he makes himself, and the amount of kablooey his larger battles cause. Also, the not trusting him bit isn't purely because he killed Justin in self defense like in the books, but also because he was taught by Justin in the first place. This Morgan is far from Harry's biggest fan, but we go from "he broke a law, forget why he did it, Off with His Head!!" to "yeah, he mostly does what's right, but he's got no regard for The Masquerade, he was the student and relative of a Big Bad, and ye gods, the property damage! Keep an eye on this one."
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.
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.
Slade Wilson (the comics Deathstroke) in the island flashbacks completes the Power Trio with Ollie and Shado. Too bad it couldn't last.
In the Indian adaptation of the American series 24, the Nina Myers character (Nikita Rai) is loyal, stays by the cause of the show's CTU (named ATU) and does not kill this show's version of Teri (Trisha).
In The Vampire Diaries, Caroline goes from a vicious bitch who tries her utmost to ruin Elena's life to a sympathetic character. She becomes outright heroic after becoming a vampire.
Supernatural features a twist on the Biblical story of Cain and Abel that paints Cain in a much better light: Cain killed Abel because Abel believed he was talking to God, but was actually talking to Lucifer, who intended to trick Abel into giving up his soul. Cain offered his own soul in exchange for Abel going to Heaven, and Lucifer accepted on the condition that Cain kill Abel himself.
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 Mega Man Battle Network series as a whole, most Navi counterparts of the Classic Robot Masters are mostly neutral at worst, but some actually do start out as villains (at first). Most prominent of these is Dex and his Navi GutsMan.EXE, who starts out as a bully, but becomes part of the True Companions.
Yoshiya "Joshua" Kiryuu is a smug, manipulative jerk in the The World Ends with You that drives the protagonist up the wall. Not to mention that Josh kills the protagonist twice, and the entire plot of the game is kicked off by his desire to erase Shibuya. When he shows up Kingdom Hearts, he's significantly nicer and much more helpful to Sora. It's almost bizarre, considering that the other TWEWY characters still have the same personality, more or less.
Joshua Graham from Fallout: New Vegas was originally supposed to be pure evil (this was in the scrapped Van Buren edition). In New Vegas, however, he is one of the Big Goods of the DLC Honest Hearts, although he still has some Blood Knight tendencies.
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 JoJo, 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.
One of the specialties of B: TAS was lending depth to villains whose comics incarnations were essentially doing things For the Evulz. The Mad Hatter has no backstory in the comics, but was introduced in the series as a victim of Love Makes You Evil; minor gimmick crook Mister Freeze's sympathetic reimagining was so successful it was later imported into the comics, albeit with Darker and Edgier elements.
Also Harvey Bullock used to take bribes in the comics, the animated Bullock claims he would never do that. Bullock is a pure good guy, a Sympathetic Inspector Antagonist who really wants to make Gotham a better place and just doesn't realize as yet that that's what Bats is doing too.
Animated Gotham's Mayor Hill was also not corrupt like his comics counterpart.
Andros Stark (the future Iron Man) was depicted as a futuristic superhero, and only battled Tony Stark in order to save the timeline, and knew if he succeeded, he himself would most likely vanish with the Bad Future he came from. In the comics, Andros is a psychotic supervillain who made a mockery of Tony's legacy.
Obidiah Stane, while still a villain and Jerkass that's willing to work with criminals, frequently shows he still has standards while his comic book incarnation was a straight up villain.
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.
The same could be said about Skurge the Executioner. While his personality is more-or-less the same, here he's just hunting Spidey because of a misunderstanding caused by Loki, rather than a Mad Love for the Enchantress as in the comics.
Another case would be Norman Osborn, aka The Iron Patriot, who is a genuine hero, and Norman's attempt to atone for his actions, both as a Corrupt Corporate Executive and as The Goblin, and in general, Norman, at least in the post-goblin pre-re-goblin stage is both attempting to be a Hero, and a good father to his son.
In the original comics, Sha Shan Nguyen started off as a Spider-Man villain named Sister Sun. In Spectacular, she was a normal high school student and Flash Thompson's Replacement Love Interest.
Also with Frederick Foswell. In the original comics he was the crime boss known as The Big Man and after his release tried returning to crime before going up against the Kingpin, making a Heel-Face Turn, and ultimately sacrificing himself to save J. Jonah Jameson. In the show he's a journalist on the up and up from the beginning.
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.
Cable's son Tyler. In the comics he was an Antagonistic Offspring and eventually became a supervillain going so far as trying to follow in Apocalypse's steps. Here Tyler is a straight-up hero and he and Cable are very close. Probably Justified via Stryfe, whose actions caused their relationship to go sour in the original comics, being Adapted Out.
The titular turtles are a lot more noble inthecartoons than the original comic. The original Mirage Turtles were assembled by Splinter purely to avenge Hamato Yoshi by killing the Shredder. Not that the Shredder isn't bad, but the Turtles were originally trained for the purpose of a revenge killing, instead of the state in the shows (where though there's an additional element of It's Personal because of the Shredder's role in the backstory, they are mostly fighting him because they're the good guys and he's actively doing something bad today. This even goes for the Darker and Edgier 2003 series where the backstory is taken practically word for word from the comics.)
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.
In the Marvel Comics universe, Berzerker was a minor villain and member of the Morlocks. In 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 random 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.
Arcade, in the comics, is an assassin who entraps victims in game-like deathtraps he calls "Murderworld". In Evolution, he is an ordinary high school gamer kid. He is manipulated by Mystique into hacking into the danger room computer in the belief that it's a sophisticated videogame. He endangers the X-Men, whom he believes are game characters. His real name is Webber Torque but calls himself Arcade. Once he realized what he was doing, he regretted his actions and was forgiven by the X-Men.
Shows like Wolverine and the X-Men and the 2011 series portray Emma Frost in a more sympathetic light. Completely turning her into a straight hero rather than a byronic one. Basically, if it was written before her comicverse Heel-Face Turn, she'll be completely evil with no sign she could ever be good; if it was written after, she'll be completely good with no sign she could ever be evil.
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.
The Aquaman villain Black Manta is reimagined as a sophisticated and somewhat noble villain who has numerous Pet the Dog moments with his subordinates, particularly his son. In the comics, he was utterly heartless.
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 is implied to 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.
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. He even ends up experimenting with innocent people in "Doopelganger", and he completely has fun terrorizing and punishing his victims. (Here's where we remind you that "the character need not become an actual hero, just nicer than they were in the original." Animated Pyg is very very bad. Comic Pyg is worse; For the Evulz out-evils Well-Intentioned Extremist, even one who is clearly having a lot of fun.)
Man-Bat is also a full-fledged ally of Batman instead of an occasional foe. It helps that Kirk Langstrom can control himself as Man-Bat, and was only forced to attack Batman when he was drugged by Pyg. Guess who's a founding member of the Outsiders?