In Whateley Academy stories, during the Halloween invasion, we get at least two or three. Deathlist, a monstrous cyborg of superman-level power and the most horrifying villain in the Whatelyverse, makes the mistake of attacking the school and threatening the children. By the time Dean Carson (aka Lady Astarte) gets through with him, the only thing left of him to escape is his head. Jimmy T, a generally peacable shapeshifter, finds out his house of misfits, Hawthorne, is being raided by troopers looking to take "samples" from the helpless students, turns into fricking GODZILLA and stomps a mudhole in the forces there before then turning into a giant amoeba and eating an attacking dropship (though he did leave the soldiers in it alive, if mortally terrified, in the end). All over the campus were mother hens ripping bad guys a new one....
It is safe to say that Strega overreacts a bit when her daughter is kidnapped: she lays siege to Paris, destroying the headquarters of the group who are holding her, turning hundreds of tourists to glass and threatening to use a sonic weapon on them, and either beating up or subverting a half-dozen of Europe's most powerful superheroes.
Hey, at least kiwi aren't that nasty. Right? Right?..
Do not threaten Strange Little Band's Addison Harris's children. Not unless you are prepared for a world of pain anyway.
Like the so very many Papa Wolves on the site, Lindsay Ellis (The Nostalgia Chick) will crush you if you hurt her friends. Her character might hate children and would be willing to see the fictional ones die, but hurt an animal and you'll see some damn scary Tranquil Fury.
Chakona Space gives us Chakats. It's programmed into their DNA. Seriously, ten fur-hating rioters vs. two Chakats in child-defense mode. The rioters felt outnumbered. And since they're Hermaphrodites they can also qualify as Papa Wolf.
Soniqua, Sonic's and Mother Brain's daughter in Sonic For Hire, is this towards Sonic. Anyone who threatens or attacks Sonic will be mercilessly murdered by her.
This lioness. "Don't you dare" indeed. A video by BBC Worldwide, "Hunting Lessons". Little cubs Lionas and sister Suki go out for a hunting lesson with their mother only to be faced with a wildebeest attack. Video taken from wildlife adaptation 'Pride'.
A tad downplayed in the sense that Bunny would have gone overboard to protect them during the events of Bunny's Maternal Instnct but she would have indeed killed Madgie if she saw the absolute need to. However, she did give Madgie a hard slap in the end and had enough power in her that she not only outran the car that her sister was driving but stopped it without her sister slamming onto the brakes.