The unofficial mascot "Commie Bunny" for China's armed forces is a rabbit. Because Tu Gong (Rural Communists) can be seen as a pun of Tu, rabbit. There has been a web series on China's modern history Call of the Rabbit: Modern Communism which depicts China as a rabbit while all other countries used more traditional animal stereotypes.
Devilbunnies are an entire web community of people writing stories based on the idea that cute fluffy bunnies are taking over the entire world and making it cute and fluffy for their own nefarious purposes.
The Whateley Universe has a toy cabbit owned by Tennyo — which conceals quite a few blades and needles inside itself, and can exert three hundred pounds of force through each (while unerringly passing through gaps in armor) when it's being animated by Jade.
Then there's Dragonrider's pet (which she created herself): Pern, a cute little dragon the size of a housecat. If Pern gets really angry, he grows. He can reach a thirty-foot wingspan with claws that can rip through granite.
Kierkegaard in Dragomirs Diary is a penguin wearing a top hat. Fantastic. Get to know him, though, and you discover that he's surprisingly adept at murdering things with his small trident, and may have the ability to transform into something far less cutesy.
This Gallery folder is named Killerbunnies and, yes, they are literal killer bunny girls of varying ages and straddles the lines between cute, horrifying, and utmostly creepy. Some of them are rather cute or Ugly Cute and wouldn't seem like a threat, that is, until one learns the hard way.
Of course, This seems to be played to a hilt with Jeanne, in that while Creepy Cute, a normal person wouldn't suspect that she's dangerous, especially since some either think she is a doll or a little girl. In that vein, Valeriemissy is not someone would think twice of, until it is too late. However, that depends on whether or not she says something that one may find unsettling.
Reverie doesn't look too dangerous, actually, she kind of verges on being rather Creepy Cute, even with the Exotic Eye Designs and whatnot, however, she wears a biohazard symbol for a reason, as she is some kind of plaguemistress. To top it off, her backstory mentions her as being the apparent Patient Zero in a sudden rabies outbreak.
The Bunny Invasion series is made of this trope. It features a man named Mr. Frost going up against a horde of homicidal bunnies led by the Bunny Queen...or in the Easter Special's case the Easter Bunny.
In The Gamer's Alliance, Plushiebunny's first form looks like a cute and harmless black rabbit. It couldn't be further from the truth as he quickly reveals that he is indeed one of the God of Beasts's deadliest creations. There are also the monsters of the woods who turn out to be pink and fluffy bunnies; they are so vicious and terrifying that they make even an archmage and a demigod flee in terror.