Villains' Absolution/Examples

Cartoons, Manga and Anime

 *  My Little Pony :
 * Nightmare Moon: Twilight Sparkle and her best friends used the Elements of Harmony to transform Nightmare Moon back into Princess Luna.
 * Starlight Glimmer: Twilight Sparkle brought Starlight Glimmer into the terrible future after another failed attempt to restore the past, but Starlight was persuasive for cutie marks costed Starlight her only friendship. So Twilight offered Starlight her friendship.
 * Sunset Shimmer: After Twilight Sparkle and her human world friends used the elements in them to defeat Sunset Shimmer, changed back from a demon into normal, she immediantly shed tears and apologizes for her actions. Later, Sunset Shimmer implored the human Twilight Sparkle to do the same after the latter's freak accident that turned her into violent and destructive being called Midnight Sparkle.
 * Chirn: As soon Chirin invaded his childhood farm, he saw a lamb that was like him when he was young and his mother saving him. He then had some second thoughts, but the wolf did had the same beliefs, so Chirin stopped him, saving the sheep for he remembered he's the wolf who killed his mother. Sadly, in spite of his redemption, Chirin's training that resulting his transformation into a monstrous being that he became has condemned into a half-life for the rest of his life (his childhood farm inhabitants exiled him for how monstrous he had become).
 * Terra: After the Teen Titans revealed to survive her attacks, Slade revealed his true color by abused her and even showed lack of concern with her well-being, pressured her enough to went against him.
 * Jinx: Kid Flash charmed her saying, she does not have to be the bad guy.
 * Dark Heart: When Dark Heart was attacking the Care Bears, he hit Christy as well, and he started to feel remorse since she save him from drowning.
 * The Grinch: His in How the Grinch Stole Christmas is no doubt one of the most famous absolution in history. After the Whos in Who-Ville sang without the presents, he began to realize that Christmas isn't about presents with the guilt for his evil act hurt him so much that it feels as if his heart become larger.
 * And in The Grinch Grinches the Cat in the Hat, the Cat in the Hat along with the other troubled people reminds the Grinch about his mother, and then starts feeling remorseful.
 * Prince Zuko: After some time in the fire palace and learned that how Fire Nation become monstrous forces revealed to be rooted from Sozin's betrayal against Avatar Roku (whom later reincarnated into Aang), Zuko realizes that he should join the Avatar gang, though he succeed to gain their trust once he aid Katara to confront her mother's killer.
 * Mai and Ty Lee: Mai went against Azula for the love of Zuko and Ty Lee went against Azula for Mai, inadvertly exposed the fact that whatever bond that they share with Azula all this time was fake.
 * Kraehe: Kraehe took a glimpse of her past and discovers who she really is: not the daughter of the Raven, but an ordinary girl. With that she lost her Kraehe side and permanently stayed as Rue for good.
 * Lord Business: Emmett tells Business that people's creativeness are wonderful, he's one of the greatest people who ever lived and he does not have to be the bad guy whom limited everyone's creativeness.
 * Iago: In The Return of Jafar, Iago got fed up with Jafar's abuse and joins the good guys for his own gain, and eventually stars to actually warm up to them, and eventuaully redeems himself by kicking Jafar's black lamp into molten lava, destroying him forever.
 * Carface: In An All Dogs Christmas Carol, after the visits of Charlie, Itchy and Sasha, Carface sees the errors of his ways and decides to stop Belladonna.
 * Scalawag and Igor: After Pinocchio saves Scalawag and Igor from the Pike, they start to have second thoughts about selling him to Puppetino and the Emperor of the Night.
 * Peridot: In Steven Universe episode "Message Received", she joins the Crystal Gems by insulting Yellow Diamond and calling her "clod" after refused to destroy the Earth with the Cluster.
 * Bismuth: In Steven Universe episode, "Made of Honor", she joins Ruby and Sapphire's wedding after discovering the truth of Pink Diamond and also becomes a permanent member of the Crystal Gems.
 * Janja: Becomes surprised when Jasiri saved from certain death, leaving him hesitant when she then asked him to join despite his refusal but leaving her sure he will come through.

Live-Action Movies

 * Darth Vader: His is no doubt one of the most famous absolutions in history. When his son, Luke Skywalker was being tortured by Emperor Palpatine, Darth Vader sacrificed himself to save Luke by throwing Palpatine into the pit. As he was dying, Vader asked Luke to remove his mask so he can see his face for the first and the last time.
 * Winter Soldier: Having this once he remembered his past self and saved Steve Rogers from drowning, and set out to destroy HYDRA's assets that used to brainwash him. Unfortunately, returned to the good side by his own terms is not enough to retain his good self due to HYDRA has arranged a fail-safe programming in his brainwash procedure where he would revert to his brainwashed self for limited amount of time via trigger words.

Literature

 * Ebenezer Scrooge: His forgiveness is no doubt one of the most famous absolutions in history. After the visits from the first two spirits and seen what the Ghost of Christmas Yet to Come shown what will his future be like, Scrooge apologizes for all the wrong he did and he will change and honor Christmas in his heart for the rest of his life.
 * The Once-Ler: The Once-Ler realizes the errors of his ways (a little too late) when he chops down the last Traffula Tree of them all.