was noble, honorable and righteous knight of the Silver Hand, and prince of Lordaeron, but after taking up the cursed runeblade Frostmourne, he became a malevolent, cold and ruthless death knight, led the Scourge in destroying Lordaeron, and merged with the Lich King himself.
was initially nice and friendly to Arlo after first meeting, but quickly reveals his true carnivorous nature after devouring the critter..
Initially was at first nice and friendly to Tony Stark, but later reveals his true nature where he actually wanted to permanently remain in control over Stark Industries.
Harvey Dent was loyal and honest ally and friend of Batman, but unfortunate accident, make that become a criminal as Two-Face.
was nice to Carl and Russell, but then reveals his true nature with the intent to capture Kevin.
and Bree Blackburn
were initially nice and friendly to Eliza Thornberry, posing themselves as zoologists, but later reveal themselves to actually be ruthless poachers.
Commander Lyle Tiberius Rourke
was initially nice and friendly to Milo Thatch for most time, but later reveals his true nature with intent to get the Heart of Atlantis.
at first seemed to be loved brother to Eddy, but quickly reveals his true sadistic nature by mercilessly abusing his brother.
for most time was nice and charming to Anna, but later reveals that he never loved her, he was just manipulating her to take the throne for himself. He then locks her in the room to freeze.
was at first nice to Pinocchio, but quickly reveals his true nature by locking him in cage.
starts off being compassionate and understanding to Judy Hopps, but in the final climax, she reveals herself as the mastermind behind the savage attacks.
started off appearing as a compassionate and understanding teacher to the Mystery, Inc. Gang, but revealed her evil plot to seize power over Tokyo and resurrect the Black Samurai.
Lotso initially acted like what his name implies towards Woody and the gang, but later reveals his true twistedly evil nature.
was initially very loyal and nice to Madame Bon Famile but after hearing that her cats get her fortune, he decides to get rid of them so he can have the fortune himself.
Prof. Robert Callaghan
was initially very friendly towards Hiro Hamada and his friends. However, after a lab accident ends with his daughter Abigail disappearing that Hiro and his friends near the climax of the film discovered, Callaghan, sets the building on fire - presumably killing Tadashi - and escapes with Hiro's Microbots. Later, Callaghan becomes known as the supervillain Yokai, seeking revenge on Alistair Krei, whom he blames for the accident.
was initially friendly towards Woody, but later reveals his true nature as he framed Jessie for turning the TV on, and is determined to go to the Tokyo Museum with the whole Round Up Gang, regardless whether the others want to go or not.
initially acted to be the cute little rabbit he appeared to be, but later revealed himself to actually be the evil Goody Bandit.
Henry J. Waternoose III
initially was friendly to Sulley most of the time, but later reveals himself to be Randall
's chief boss to Sulley and Mike after being convinced by Randall to assist him and learning about Boo as he saw her as a threat to his business.
, Gus and Reginald
initially acted like kind elderly security guards they appeared to be towards Larry Daley, but later reveal themselves to be after the stealing the tablet of Amuk Munrah and other valuable objects, wishing to retain their health and fund their retirements, the three plan to frame Larry for the real thefts, and disabled the tablet to stop the exhibits from interfering.
started off appearing noble and welcoming, but then revealed himself as the ruthless tyrant and psychopath he truly was and reveals that he is actually Turbo in disguise.
Alejandro initially acted to be charming and nice man, but reveals his true nature after eliminating Bridgette.
Scarlett was initially a nice and wise person, but reveals her true nature as the genius of evil after taking control of the control panel.
at first was friendly, shy, kind filly, who become helpful and wise student of School of Friendship, but later reveals her true malevolent and power-hungry nature wanting become powerful pony in Equestria.
Tangier at first was nice and friendly to Russell Ferguson, but reveals his true nasty nature by sabotating another photo session by putting hot sauce to Russell's food.
Varian was initially an nice, friendly and helpful ally to Princess Rapunzel and her friends, but later reveals his true vengeance-seeking colors to Rapunzel betraying her.
Creek at first was nicest, most friendly and positive Troll in all of Troll Village giving other Trolls advice, but then reveals his revealing treacherous nature betraying his own race and become Chef's assistant as long as he survives.
Ernesto de la Cruz
was initially nice and friendly to Miguel, complimenting him and sharing with him passion and love for music, but later he reveals his true nature to Miguel after admitting his murder of Hector and stealing his fame.
Ben Ravencroft first appeared to be a charming author who wanted Mystery, Inc.'s help to find a book belonging to his ancestor Sarah Ravencroft to she was a good women not a wicked witch, but was revealed he was really using them to find the book so he can become powerful
Jack Rabbit was best top agent of T.U.F.F. and good partner to Kitty Katswell, but reveal his greedy nature by draining Kitty's knowledge of T.U.F.F.'s secrets from her brain and selling them to Verminious Snaptrap in exchange for money.
Andrea Beaumount first seen as an innocent, sad woman visiting Gotham City after ten years and wants to start her relationship with Bruce Wayne all over, but is later revealed as the deranged, murderous Phantasm, seeking revenge on the mob gang who threatened and killed her father
at first was friendly towards Edd, Matt and Tom, but later revealed his true colours and decided to cause terrorism by revealing his robot.
Anakin Skywalker at first he was a Jedi Knight fighting on the Light side of the force and trained by Obi-Wan Kenobi, but by Emperor Paplatine joined to Dark Side of the Force and he become the nestest Dark Lord of Sith known as Darth Vader.
was originally friendly towards Sonic and his friends, but later, she reveals her true nature by joining with Scourge the Hedgehog and starts to betray the Freedom Fighters, which included poor Tails.
Cassie Rose was initially friendly and harmless to Jesse's gang and the Youtubers for most time, but later reveals that she is The White Pumpkin.
DJ was initially helpfull to Finn and Rose for most time, but later reveals that he serve the First Order.
Evelyn Deavor started out as a friendly, loyal, and kind-hearted lady who is eager to help others. She is also laid-back at times. Unfortunately, she later reveals her true nature when she unmasks herself as the real Screenslaver. During the confrontation, she revealed that she never supported her brother's mission in bringing supers back into public and plans on keeping them illegal forever.
was initially nice and friendly to Flint Lockwood for most time, but later reveals his true nature with the intent to get the FLDSMDFR.
Scarlett Overkill for most time was nice and charming to Kevin, Stuart and Bob, but latter they did failed in stealing the crown, she was angry with them and locks them in the warehouse.
Sentinel Prime was the original leader of the Autobots before Optimus until the war for Cybertron left him no choice but to form a partnership with Megatron. However, it becomes clear that he blackmailed Megatron so he could take over the leadership of the Decepticons for himself.
was initially a good father and loving husband, but after descending into madness in the Overlook Hotel, he becomes a psychotic killer.
Dr. Sebastian Caine
started out as a normal scientist, but after lying to the government and testing the invisibility serum on himself, he becomes a murderer.
was initally an ally to James Bond after being sent by M, but later reveals that she was the one who betrayed James Bond and that she works for Gustav Graves.
In the beginning, M was first seen as a head of security who sponsored the League of Extraordinary Gentlemen who recruited various figures like Alan Quartermaine to stop the infamous Fantom from starting a world war, but was later revealed that he was the Fantom and was tricking the League so he can get the essence of each member for his plan to rule the world. And he was also later revealed as Professor James Moriarty.
Dorian Gray was first seen as a charming immortal who later joined the League of Extraordinary Gentlemen, but later revealed that he was a spy for M, sent to steal the essence of each member
Rameses was nice to his adoptive brother Moses, but later he become arrogant.
Frost was introduced friendly and nice, but he reveals his true nature for "killing" people and stealing treasures.
was introduced friendly, but during the climax of Revenge of the Sith
, he is revealed to be Darth Sidious.
was introduced as Buzz's partner, but after revealing that he is a double agent and the traitor of Star Command, he is one of Zurg's minions.
Simone Lenoir and Lena Dupree were first seen as innocent hostesses of a bayou island asking Mystery Inc. help solve a mystery there with Jacques as their ferry man, but were later revealed as monstrous werecats ought seek the life force of Mystery, Inc. so they can be immortal.
Monika was introduced as friendly and polite to protagonist. However, she reveals her true nature to protagonist and her real plans to eliminate Natsuki, Yuri and Sayori to be with the protagonist forever..
Tobias Beckett starts off being a friendly, wise and helpful mentor to Han Solo, but later reveals himself to actually be greedy, egotistical and manipulative cheater who was intent on make a profit unsold coaxium.
Makoto was introduced to be polite, cheerful and friendly towards others, including the Minato brothers and their sister, Asahi, but it soon revealed that he is an obsessive, egotistical and power hungry hero-wannabe who wanted to abuse the power of Ultraman Orb Dark to gain his fame as the "real" Ultraman.
Mizuki used to be friendly towards Naruto and gives him an "advice" to pass the exam, but it was revealed that he only used Naruto to manipulated him to steal the sealed scroll and give it to him just for being loyal to Orochimaru.
The A-Squad Rangers
were introduced as reinforcements of S.P.D., but later betrayed Commander Kruger as they reveal themselves to be traitors of S.P.D..
started out as a loner and an outcast student who is harshly treated by everyone at school and even her own mother Margaret. Later, she becomes a psychotic murderer after the infamous blood prank during the school prom.
starts out when he is friendly towards his cousin Matt and his friend Steve. But later, he reveals his malicious nature to Matt during the final climax and calling himself an "Apex Predator".
Buddy Pine used to be an enthuastic fanboy of Mr. Incredible who wants to become his sidekick named IncrediBoy. Years later, he become a supervillain named Syndrome who wants to get revenge on Mr. Incredible for rejecting him for all the years.
Bago Go started out as a friendly and cheerful alien who likes to sell illegal weapons to his customers, like his favorite one Adu Du. But later, he reveals his true egotistical and greedy nature when he and his brothers arrived on Earth.
Giffany first introduced as a friendly and positive girl who becomes one of Soos' friend. Later, she reveals her true lovesick and overbearing nature to Soos that she only wanted to win Soos' affection so she can be with him forever.
Dick Hardly is introduced as kind and friendly person, but later reveals that he is a greedy, malicious and manipulative cheater.
is introduced pleasant and kind, but after testing the serum on himself as well as driving to insanity, he becomes a supervillain known as the Green Goblin.
is introduced as a photographer for the Daily Bugle, but after getting fired for forging a photo of Spider-Man robbing the bank as well as losing his girlfriend, Gwen Stacy to Peter Parker and the symbiote lands on him, he becomes a supervillain known as Venom as he gets revenge on Peter for making him lose his job and his girlfriend.
starts out as a Jedi apprentice to Yoda as well as a Jedi Master to Qui-Gon Jinn, but later turned to the Dark Side and joined the Sith.
Henry Evans started out as a friendly and calm towards his cousin, Mark. Later, he reveals his cruel and sociopathic nature that he is indeed a murderer who wants kill his family no matter what it costs.
Clayton initially posed himself to be a kind (if somewhat impatient) guide to Tarzan, Jane, and Professor Porter, but later reveals to Tarzan while locking him up that he planned to cage all the apes from the very beginning and sadistically praises Tarzan that he owes it all to him.
Will Teasle first appearing as a well respected and kind sheriff, Teasle eventually shows his true nature when he arrests John Rambo for no vagrancy (even though he was innocent) and lets his deputies abuse him to his breaking point which nearly leads to the destruction of the town..
While this TV pet show host may look like Happy Chapman lives up to his name, in reality, he is an arrogant, selfish, and greedy jerk who abuses his assistant Wendell, and is not satisfied with his job as a TV pet show host. His original star pupil was a famous cat named Persnikkity, whom he grew tired of due to his allergies and then puts Persnikkity in the city pound. Chapman wants a dog to star in his show so he can overshadow his more successful news anchor brother Walter in fame. So he steals Odie for his own gain and then uses a dreaded shock collar on him, and even laughs at the dog's pain from powerful jolts.
Darla Dimple initially appears as a sweet and darling little girl who loves animals, but reveals herself to be a complete egomaniacal, psychopath, and rotten to the core spoiled brat who wants the spotlight to herself and is afraid Danny and his animal gang will ruin it and is determined to stop them at all costs.
Gage Creed used to be a sweet and innocent child until his death. Later, he becomes a ruthless serial killer who was possessed by by the necromatic force Wendigo infested at Pet Sematary and was full of spite and cruelty.
Jenny first appeared as a friendly and shy woman who works as M.A.T.A.'s TEKNO member. Later, she was revealed to be Numeros' spy who worked with Uno.
Gwen Grayson first appear as the beautiful and friendly class president of Sky High who Will Stronghold has a crush on. But later revealed to be the villainous arch-nemesis of the Commander, Royal Pain, seeking revenge
Baylor Hotner first appeared as an actor from Hollywood but rampaged the city as Crybaby Clown to perfect his role in his new movie.