(Tomo returns from a full throttle run around school in a cute cat costume) Chiyo: Where did you go, Tomo? Tomo: Advertising. I was sprinkling cuteness all over school. Yomi: Topped off with a nice heavy dash of scary. — Azumanga Daioh
Road Kamelot in D. Gray-Man certainly qualifies. She looks no more than twelve - yet in one of her first appearances she stabs the main character's eye with a candle, then licks the blood off afterwards.
Doubt - if you read later on... Grotesque cuteness indeed.
The main School Days series was already infamous for its bloody finale... And then comes the Magical Heart Kokoro-chan OVA, with the eponymous loli helping pilot a giant Hello Kitty, chainsaw-wieldingCombining Mecha, ripping apart the enemy and drowning the city in a sea of blood. Yeah...
Many of the creations by Henmaru Machino, where Hentai and extreme sexual pathology meets Kawaii.
The manga Death Panda by the notorious Gorn artist Uziga Waita.
The theme park from the Mad Pierrot episode of Cowboy Bebop uses this a lot. Some scenes of the destruction of cutesy park mascots, and their use as weapons, are Accidental Nightmare Fuel.
Max in Sam & Max: Freelance Police — threatening cruel and unusual punishments while extolling his own "marketability".
Marvel Zombies Returns 1 has Zombie Spidey in a world that is like a late 60's- early 70's Spider Man comic. Everything's so happy UNTIL SPIDEY RIPS OUT KRAVENS THOAT WITH HIS TEETH!!
Everyone (except Zombie Spidey and Sandman) ends up infected and killed or just eaten alive.
There's a certain element of this to V in V for Vendetta. Round, pink cheeks; Eyes Always Shut; huge smile; little upturned nose (at least in the comics); silky, shoulder-length hair... and he kills people with his bare hands!
In Dean Koontz' book, Brother Odd, the title character encounters a manufactured animal who is the epitome of mindless cuteness. Mindless, in that it literally has no mind or soul and is therefore profoundly disturbing rather than cute.
Live Action TV
The suicidally depressed giant teddy bear in the Supernatural episode "Wishing Well".
The player characters in the Playstation Network game Fat Princess are adorable chibi fighters, wizards, and such... who bleed copiously when injured or killed.
Robbie the Rabbit, the mascot of the Silent Hill Amusement Park is a pink bunny wearing a blue overall whose most prominent feature is the blood-stained mess on his mouth and clothes. Heather from the third game says that "it is more creepy than it is cute". Coming from a girl who has deadpan snarked her way throught the eponymous town, without batting an eye to the overall gory insanity around her, this says a lot.
Conker's Bad Fur Day and Conker Live and Reloaded.
Dahlia Hawthorne in Phoenix Wright: Trials and Tribulations is extremely cute and beautiful, even with pure white butterflies flitting about her. However, at the end of the first trial, after she's been accused of murder, she actually incinerates her butterflies with pure rage.
The Creeper from Advance Wars: Days of Ruin. Flowers are pretty. Which makes a bio-weapon that makes flowers sprout from underneath and fatally turn you into a floral display in a most painful manner all the more disturbing.
She wrenches open the lid of a nearby sarcophagus, and countless articles of stationery, toiletries, and household goods with her face on them pour out. My god, she's everywhere! Aargh!
In the Kingdom of Loathing universe, seals aren't adorable fuzzy flopping creatures as in real life; they're hideous, shambling, bloodsucking monstrosities that happen to look like adorable fuzzy flopping creatures, one of which looks more like a mutated leech than any land mammal. That said, one familiar you can acquire as a Seal Clubber is an Adorable Seal Larva, which intersperses descriptions of it sucking the blood from your opponent and bursting into an enemy's corpse so it can regurgitate a healing fluid into your body with gushing about how adorable the thing is.
Considering how cartoony the characters in the Metal Slug series are, some of them die in fairly bloody ways.
Charby the Vampirate is described as an ultra-violent Saturday morning cartoon, with adorable characters who will occasionally eviscerate or suffocate their many victims, brutally, with no Gory Discretion Shot. The combo is especially obvious with Mye, the zombie girl who smells sweet despite 315 years of decay, not to mention the unhealed slit in her chest where she got a sweet heart transplant. Her Evil Eye are bubblegum pink.
Mye isn't decaying,(she is a traditional zombie, not a Hollywood/Romero zombie)the sweet smell is candle wax and gummy bears, two things she spends a lot of time with. And her brother's eyes are pink, too!
Erf World pretty much runs off this, with the incredibly cute and adorable-looking, child-like midgets engaged in brutal, unending wars for no real, discernible reason.
The Unspeakable Vault (of Doom) is a Lighter and Softer look at the Cthulhu Mythos—for instance, its cartoonishly-drawn "Cthulhoo" says "yum yum" every time he eats an unfortunate cultist. But it's still the Cthulhu Mythos, and the gore factor actually goes up compared to Lovecraft's work. It'd be Mood Whiplash if the death and dismemberment weren't so heavily integrated into the comic alongside the silliness.
The other Trolls do as well, albeit to a lesser extent. This seems to be a fact of which they are both aware and proud, given that they decide to call themselves "Team Adorabloodthirsty."
Heck, Homestuck in general qualifies. It starts off simply being about a kid who is celebrating his thirteenth birthday by playing a new game. Then the game turns out to cause The End of the World as We Know It and summon monsters wearing jester hats to torment the protagonist, and it only gets worse from there on out. It becomes more clear later on, with Jack Noir slaughtering an entire army, a children's show's characters turning out to be representations of "horror terrors" and comic relief character Gamzee going Ax Crazy and deciding he needs to kill all his friends.
The diaries of Vriska's ancestor*
A distinction granted near-legendary status since troll reproduction precludes the notion of actually knowing who your direct ancestors even are
suggest that this is not only normal, but expected and encouraged of trolls of Gamzee's rank; in troll society, such traits are considered the mark of strong leadership skills.
In an attempt to tone down the violence and make the strip more viewer friendly (or so we are told), Kagerou brings us "cute chibi blood".
The Order of the Stick: The stick figure art makes everything look much cuter than it would in a more realistic style. And yet you still get characters like Xykon and Belkar and quite a bit of violence. In particular, Tsukiko sleeps with an adorable Xykon plushie, and Belkar is a fuzzy-footed halfling of chibi proportions who gleefully stabs everyone who crosses him or has something he wants.
Sonichu unintentionally falls into this. It looks a lot like something your seven year old child would draw, with creatures that are a combination of Sonic the Hedgehog and Pokémon, with an Author Avatar that is the mayor of the town and cartoon-y villains. However, it features graphic sex scenes and true to this trope, scenes where a bunch of Internet trolls are tortured to death, including one getting drilled in the groin by a little girl.
Web Original
Ruby Quest is more or less about taking some cute animal people and then breaking them physically and mentally in horrible, horrible ways.
This is pretty much the entire design philosophy for all the monsters in Mortasheen, and the author's list of favorite monsters shows a definite personal preference for that style.
The baby goldfinches that eat Hopper in A Bug's Life. It's not gory, but pretty gross.
Drawn Together, with the characters Strawberry Sweetcake and Ling Ling.
The Grim Adventures of Billy and Mandy once had an episode entitled "Wishbones" in which a skull granted people's wishes, with results of varying degrees of misfortune. Pud'n's wish was that he had a little talking bunny that always loved him. Although the bunny wasn't THAT cute, it proceeded to chase Pud'n around, beating him and trying to murder him multiple times, ending with HALF OF HIS FACE BLOWN OFF OF HIS HEAD IN DETAIL WITH THE WORDS "Sometimes love hurts, Pud'n, and I love you....to deeeaaaattthhh...." as he hopped towards Pud'n slowly. Oh, and this is a children's show.
