- Monty Python and the Holy Grail
- The Rabbit of Caerbannog. Ironically, Arthur and his knights are warned repeatedly by Tim the Enchanter about the power of the rabbit. They don't listen, and he laments how no-one listens to him because "it's just a harmless little bunny!""Look at the bones!"
- An implied example in the same movie would be the Vicious Chicken of Bristol which Sir Robin nearly stood up to, though given that it's Sir Robin, the Chicken might be a case of Deathbringer the Adorable (though he's never shown cowering and running away from anything harmless-looking in the movie).
- The Rabbit of Caerbannog. Ironically, Arthur and his knights are warned repeatedly by Tim the Enchanter about the power of the rabbit. They don't listen, and he laments how no-one listens to him because "it's just a harmless little bunny!"
- Given a Lampshade Hanging in Galaxy Quest: while the rest of the crew is Squeeing about how adorable the child-like alien miners are, the very Genre Savvy Guy worries, "Oh, sure, they're cute now. But in a second they're going to get mean. And they're going to get ugly somehow. And there's going to be a million more of them." Moments later, he's proved right.
- Early in Barbarella, the title character is similarly menaced by a group of dolls whose mouths show very pointy teeth. Later in the movie, she is nearly killed by vicious killer budgies (parakeets).
- The Mogwai in Gremlins, except the original Gizmo; fluffy and adorable, they are cruel tricksters who eventually turn into hideous (yet still somewhat cute) monsters which go on a deadly rampage. Indeed, every imaginable variant on this trope seems to run through most, if not all, Gremlin folklore.
- Jurassic Park:
"Did you find him?"
- Dennis Nedry in Jurassic Park gets killed by a fairly harmless-looking dilophosaurus... after it spits poison in his face, then ambushes him when he tries to get back to his truck. It should be noted that dilophosaurs probably couldn't do that. Then again, we really have no way of knowing, but they certainly did not have those nifty-looking frills. Also, Dilophosaurs were much bigger than the one in the movie.
- Furthermore, there are small, harmless-near-cute-looking Procompsognathus/Compsognathus in The Lost World: Jurassic Park, whose packs are enough to turn a healthy adult male into...
"...Just the parts they didn't like."
- Night of the Lepus, a movie about Giant Killer Bunny Rabbits. It is intended as a horror film. Meat-eating rabbits that hunt and kill horses at one point. Three scientists grab the Idiot Ball hard to make it happen.
- The gopher in Caddyshack.
- Cats & Dogs had their antagonist Mr Tinkles—the cute cat who's also a Diabolical Mastermind.
- Let's not forget Screamers. Can I come with you?
- The Vampire Pomeranian in Blade: Trinity named Pac-Man. It appears to have the split-mouth of a Reaper.Hannibal King: You made a goddamn vampire... Pomeranian?!?
- In Mom and Dad Save the World, Dick Nelson encounters a group of cute mushroom-like creatures which appear to be friendly... until he tries to pet one. It opens a huge mouth with sharklike teeth and almost takes off his hand.
- Star Wars:
- Ewoks. Yes, they're cute. Yes, they're fuzzy and huggable and all that. Yes, they're adorable miniature bears. Think about that one. Miniature bears! With astonishing engineering skill for a neolithic materials base, extensive knowledge of sophisticated warfare, and a willingness to kill and eat other sapient beings. Think of them as armed, sapient, and highly sophisticated sociopathic bipedal giant koalas who regard you as potential food, and you'll start to understand exactly why the Ewoks qualify for this trope. Still don't believe us? Go read Apocalypse Endor (Star Wars Tales 14). That's right — Endor is The Empire's 'Nam.
- Yoda is the cute little floppy-eared goblin that talks funny. Even Luke and R2-D2 thought he was harmless when they met him. In actuality, he is a badass Jedi that can pull a triple backflip and chop off your head before you blink. He's undoubtedly one of the strongest and most skilled Jedi in the history of the galaxy too - almost an even match for Darth Sidious, one of the deadliest Dark Siders ever.
- The title character in the Leprechaun series.
- Chucky from the original Child's Play films (before his Frankenstein makeover).
- On the good ship Serenity, who's the most dangerous crewman? Is it the wily and wary captain Malcolm Reynolds? The calm, stoic, and deadly first mate Zoe? The giant, burly Jayne with enough weapons to outfit a revolution? Nope. Look behind them. Not at the pilot, or the preacher, though they're deadly enough in their own right. Not at the mechanic, and not the doctor or the Companion. Yeah, There. That teenage girl in the back, with the unwashed hair, pale skin, glazed and distracted eyes, who's mumbling something about hummingbirds? Her name is River. Get on her bad side, and she will fucking end you.
- This Spanish student film uses this trope quite deliberately with its genetically altered Death Rabbit.
- Played with in Gozu. You'll never know if the cute Chihuahua in fact was a trained Yakuza attack dog.
- A whole colony in The Lone Ranger. It's rather creepy too.
- Sam in Happy Accidents is terrified of tiny dogs.
- Bullitt: The mob hitman is a grey-haired man in plain clothes. His driver looks like a middle-aged accountant, but Bullitt has to work hard to keep up with him in the car chase.
- Captain Marvel: the sweet, innocent kitty Goose is later revealed to be a Flerken, an extremely dangerous creature with a Pocket Dimension full of Combat Tentacles in her mouth.
Killer Rabbit / Live-Action Films