Sealed Evil in a Teddy Bear

"Rebecca: Say Hello to all nice people, Teddy!

Teddy Bear: *With Satanic voice* I'll swallow your souls !!"

- Marik's Evil Council #2

An otherwise fearsome character gets trapped in a cutesy body. This reduces him to the status of Cuddly Mascot or (for more literal cases) Companion Cube. But there are times when he'll be able to break out the fearsomeness again -- most obviously in service to his mistress/master because that's when the seal is most likely to be loosened.

See Fluffy the Terrible and Deathbringer the Adorable; see also Sleep Mode Size. Happy Fun Ball is the inanimate equivalent.

Anime & Manga

 * Boogie-Kun from Karin is the spirit of a serial killer trapped in the body of a doll.
 * Ioryogi from Kobato. We don't know exactly what he is unsealed, but he caused a lot of trouble in Heaven, where he is hoping to return.
 * In Cardcaptor Sakura, Cerberus dozes off while guarding the Clow Cards. This causes the cards to escape, and Cerberus ends up looking like a soft toy.
 * In Dragonball Z, during the Frieza Saga, this is Captain Ginyu's ultimate fate. While using his body-swapping technique, a frog is thrown in his way, causing his own consciousness to become sealed within the frog (and the frog's mind to enter his body).
 * Well, his ultimate fate is to die in the Namek Shattering Kaboom...
 * No, he was seen on Earth a couple of times after that -- he got teleported there along with everyone else, and became king of a frog pond on the Briefs estate.
 * Notably, he cannot swap bodies if he cannot say the word. He could only take over Bulma's body because she made a device that allowed frogs to speak, and was changed back the same way as before, when frog-Bulma was thrown in the way of his body-swapping beam.
 * Pokota of Slayers is a Chaotic Good example. Though, even in plush form, is still a fully capable Person of Mass Destruction.
 * Ghost Stories (or Gakkō no Kaidan), has the powerful entity, Amanojaku, who was released from his sealed prison (courtesy of the main character's mother)due to urbanization. His freedom didn't last long as he was sealed again by accident in the body of the main character's pet cat. Most of the series has him being their snarky, initially mean spirited pet mascot.
 * A literal example in Pluto. Dr Roosevelt is the smartest AI in a world full of robots, but because he was made by the anti-robot Thracia, he exists as an inanimate teddy bear sitting on a chair. The series has several villains and he is the one manipulating them all.

Comics

 * In Marvel Comics' Great Lakes Avengers, Deathurge got trapped in the body of a squirrel.
 * Similar to the above example, one Marvel Adventures comic, Dread Dormammu, by order of a magical contract with the Ancient One, could only return to this dimension if he took the form of a rodent. Cue Dormammu returning to Earth in the form of a squirrel and attacking the current Sorcerer Supreme by dropping acorns on his head until Strange finally frees him from this restriction by demanding that Dormammu reveals his true form.
 * In Lenore the Cute Little Dead Girl there is Ragamuffin, a vampire cursed by the witch sister of his victim, who turned him into a rag-doll.
 * Johnny the Homicidal Maniac: The Doughboys. Not to mention
 * In the Hack Slash story line "Slice Hard", the slasher Ashley Guthrie came back as a small animated teddy bear.

Films -- Animation

 * In The Emperor's New Groove, the villainess, Yzma, drinks one of her own shapeshifting potions near the very end of the movie and is turned into a cute little kitty cat with an adorable squeaky voice. Quite fitting, really.
 * Doubles as a Stealth Pun Actor Allusion considering one of her voice actress' most famous roles was Catwoman.

Films -- Live Action

 * Subverted in Ghostbusters. Ray, forced to choose the ultimate destructive form for the evil entity Gozer, thinks of the Stay-Puft Marshmallow Man, the most harmless thing he could imagine. It turns out to be far from harmless.
 * Childs Play. The serial killer Charles Lee Ray is trapped by Hollywood Voodoo into a "good guy" doll called Chucky. Though he's far from helpless.
 * And then there's Tiffany about ten years later...
 * Volkonir was essentially about Sealed Good In A Teddy Bear.
 * There's the So Bad Its Good horror film "The Gingerdead Man" basically a Childs Play knockoff of a serial killer (played by Gary Busey) who's soul gets trapped in a gingerman cookie.
 * The "Jack Frost" series about a serial killer who gets doused in toxic waste and snow and becomes a killer mutant snowman.

Literature

 * The Dresden Files book Death Masks had Harry summoning a Loa to gain some information. Part of this ritual requires Harry giving the Loa a physical body to inhabit during the interview. The only usable vessel Harry has on hand, much to the Loa's dismay, is a Cabbage Patch Doll. Harry, naturally, thinks it's hilarious.
 * In the Malazan Book of the Fallen series, the mage Hairlock had his soul shifted into a puppet after he was cut in half during a battle. In this form he plots revenge against Tayschrenn.
 * Mogget from the Old Kingdom books is sealed into the form of a cat. He is in fact an incredibly powerful Free Magic spirit. And also prone to attempting murder against his master when freed.
 * One children's horror novel had an evil demon possessing the body of a parrot and attempting to make the owner as miserable as he can. After a botched exorcism attempt, it possesses his dog.
 * And again in another separate children's horror series, Bone Chillers, where the main character discovers that his new pet parrot has the power to predict doom and was responsible for the death of his grandfather. In the end the parrot is eaten by a vulture, but the vulture starts to talk, squawk and grow bright blue feathers before dying mysteriously.
 * And also in Bone Chillers, "Scare Bear" - a literal sealed evil in a teddy bear.
 * Let's not forget "The Professor's Teddy Bear," a horror story by Theodore Sturgeon, in which a monster shaped like a teddy bear helps a four-year-old named Jeremy make terrible things happen, both in the present and the future.
 * In the Harry Potter series Peter Pettigrew a dark wizard who works for Voldemort spent about 13 years masquerading as the Weasly's pet rat Scabbers.
 * Strange Attractors by William Sleator has an example involving a literal teddy bear; a character is hiding a time machine inside her teddy bear while she sleeps, and this is an important plot point.

Live Action TV
""You start to think that late at night the doll will go, ''""
 * The demon hunter trapped in the ventriloquist's dummy in Buffy the Vampire Slayer qualifies, though he wasn't restricted with a Restraining Bolt.
 * Angel's Wesley once summoned a Loa that took the form of a fast-food restaurant's burger-shaped drive-thru speaker.
 * And Angel himself was turned into a muppet in one episode. Complete with Cute Little Fangs.
 * Salem in Sabrina the Teenage Witch was originally a human Napoleon-style dictator. After his world domination plot ultimately failed, some good witches magically trapped him in the physical form of a cat.
 * Robin Williams, in A Night At The Met, claims that Teddy Ruxpin dolls are all about this trope.


 * A rather literal example existed in an episode of The Outer Limits, where a Teddy Bear underneath the bed lures a kid by having it claim that he's scared of the dark and wants him to pull it out. The boy is then sucked under the bed to his sister's horror. Foreshadowing this, the bear starts ominously stating "little boy" and has its eyes open to reveal them to be red.

Tabletop Games

 * Ravenloft has Doll Golems, intended as guardians for children... in a setting where any magical construct is essentially guaranteed to turn murderous. Although you'd have to be an Abusive Parent to force your children to be in the same room with one of these anyway.

Video Games

 * Tibbers, Annie's teddy from League of Legends, is actually a demon that she summoned and sealed. At her command, she can summon him forth in the form of a giant flaming grizzly.
 * In Tales of Symphonia, there is a small, weak summon spirit named Corrine who . Not exactly evil, but neutral.
 * There's also the Evil Teddy enemies that count.
 * Touhou's Rumia is usually interpreted as this by fandom, thanks to Word Of ZUN that her hair ribbon is a magical seal.
 * in Jak 3, when  Of course, it's towards the end, so he doesn't do much evil afterwards, but still.
 * A terrifyingly literal example appears as the third level's boss in Splatterhouse 3. See for yourself.
 * From Adventure Quest Worlds is Deady, Volatire's cuddly, demonic, wise-cracking, undead teddy-bear who is capable of slashing and blasting his way through entire armies of skeletal minions. The reason why this isn't played straight is because he chooses to appear in the form of an extremely creepy living teddy bear. The one time he is called out for it, he decides to switch into his real form...which can be pretty much summed up as an Eldritch Abomination.
 * In the Gamecube version of Custom Robo, an intangible force of destruction called "Rahu" somehow got itself trapped inside a futuristic customizable virtual reality Rock-em Sock-em Robots toy (the titular Custom Robos) while in the process of causing cataclysmic ruin to Earth, finally being rendered tangible and thus vulnerable. It's not cutesy in the slightest as Rahu is still a force to be reckoned with, but it's a force of destruction hobbled by being trapped in a child's toy.

Web Comics

 * Reynardine from Gunnerkrigg Court is trapped in one of Antimony's stuffed animals after a botched attempt to steal her body. Because the stuffed animal was explicitly Antimony's property, he finds that he can't jump to another body without her permission.
 * Loki from Sparkling Generation Valkyrie Yuuki. But while he may look similar to Reynardine, he has no leash. He is, however, still technically trapped in a cave underground chained to a rock with snakes dripping venom into his eyes. He's merely controlling the doll remotely and experiencing life vicariously.
 * In the (now-discontinued) webcomic Lowroad, Natasha is dabbling in the occult and accidentally summons an evil spirit... which possesses one of her stuffed toys. Doom-Piggy!!
 * Blair of Eerie Cuties is an adorable little blonde doll, with a grown perverted man inside. It hasn't been explained yet who or what Blair was, and how he ended up as Nina's favorite dollie.
 * And he took the trope to it's literal meaning when he disguised himself as a teddy bear so that he could take pictures of the girls during a Slumber Party.

Western Animation

 * In the season two finale of Adventure Time the Lich
 * Also, the most evil soul in the land of Ooo is . Take a moment to process that.
 * During the season one finale of Jackie Chan Adventures, Jackie uses the shapeshifting power of the Monkey Talisman to turn Shendu into a bunny rabbit. Unfortunately Shendu still has his powers even as a rabbit so he beats the crap out of Jackie and turns himself back into a demonic dragon when he retrieves the Monkey Talisman.
 * In the first few seasons of Xiaolin Showdown, Wuya is in "spirit form", which basically looks like a mask with tentacles. She's a brilliant evildoer, but since she can't do anything for herself, she has to act as sidekick and mentor for whoever's willing to work with her, even the Minion With an F In Evil.