Darken, another D&D based webcomic, illustrates that even borderline cosmic horrors shouldn't bother the daughter of an ancient dragon.
Dominic Deegan: Miranda Deegan is one of the most powerful mages in the world most of the time. When her family or students are threatened, however, she is completely unstoppable. The necromancer Rilian once took advantage of this - he betrayed the Deegans' location to his age-old enemy, Helixa, knowing that Miranda would never let her lay a finger on them. He was right; Miranda killed Helixa (with her bare hands), and although it didn't take, she made a point of finishing her off the next time they met. She took an infernomancer who tormented a friend of her son (the title character) and opened his mind to a world of arcane torture. And then she banished him to approximately the other side of the universe. This infernomancer had just attacked a classroom full of her students (she's the headmistress of the local Hogwarts) and killed three of them, though, so it's still valid.
El Goonish Shive: Abraham knowing that his opponent is half-human and half-immortal, saw only one implication, and mostly wrong one. The prospect of facing said immortal's reaction after he left her child within a hair's breadth of death somehow escaped his attention in all this haste. Immortals cannot interfere directly, but she's free to try killing him with mortals' hands...Isn't it surprising — where all those heavy boots flying toward his butt suddenly came from?
She had to be restrained to stop her from attacking Osamu, her abusive father, who everybody else is mind-numbingly terrified of because he picked up her daughter.
Far to the North: Kelu is technically an Aunt Bear, but she more than earns her title. If you threaten her kids she will beat the hell out of you with her bare hands. Even if you happen to be a massive, fire-breathing dragon.
Von Pinn. Unusually for Mama Bears, her charges are genuinely and justifiably terrified of her — largely because they understand how prone she is to violence and overkill — she is introduced trying to encourage safe behaviour in a young woman whom she is holding off the ground by the neck. However, she has never actually hurt any of the students, and nearly has a breakdown when the only way to keep one group of students safe is to go through another one. She also reveals that she was supposed to keep Agatha "safe" primarily in the sense of "preventing her from posing a danger to others."
Castle Heterodyne shows a warped version of Mama Bearness (or Papa Wolf; it doesn't really have a gender) towards its Heterodynes. While it is normally happy to help them perpetuate destruction and chaos, when they start getting self-destructive, it puts its foot down and is willing to imprison them if necessary.
Goblin Hollow: When gargoyles threaten goblins: Lily in action...and again, here. These critters are nightmare creatures made of LIVING ROCK. And she rips one in half... with her bare hands.
It's subtile, but the Condesce also counts as this. When her heiress, Jane, gets stabbed due to Aranea, she continues to snap her neck and pull off the Ring of Life that made her unkillable.
Lady Spectra & Sparky: The superheroine Lady Spectra doesn't seem to mind taking her daughter/sidekick Sparky into combat with her, but woe betide any villain who actually harms her.
An example of this and minor aversion of What Measure Is a Non-Human? occurs later when Vaarsuvius has to deal with the enraged mother of an adolescent black dragon that the party killed.
Vaarsuvius also counts, making a Deal with the Devil to have the power to save their own children from the dragon. They not only kill the dragon, but reanimate her head and use a high-level Necromancy spell to KILL HER WHOLE EXTENDED FAMILY — including eggs. According to V, that's nearly a quarter of all black dragons on the planet. This will ensure that no one in her family will come after V's mate and children again. Unfortunately, now V has pissed off Tiamat, the goddess of evil dragons. What's more, V inadvertently caused the death of many humans whose only crime was that they bore the child of a dragon (or hybrid thereof), or were related by blood to such a person, etc., etc. Vaarsuvius suffered a Villainous BSOD over that.
And, because we're not sure exactly what gender V or V's mate possesses, another Mama Bear moment goes to V's mate, who, after witnessing and perfectly understanding the above attack, still stands between V and their children holding only a stick. Inkyrius is specifically noted to be a noncombatant (a baker, to be precise) with only NPC class levels.
Ozy and Millie: When society has wronged Mrs Mudd's daughter, she will attempt to do something about it, even if it's a losing battle.
Fara relentlessly defends Rain, her transgender niece, even to the point of interfering with her own romantic relationships and getting into fights with other family members.
Donna Strongwell, in chapter 35, defends Rudy against Norman, her husband, when the latter threatens to send Rudy away after he stands up for himself and Maria.
Serix: Rees goes into this mode around broken-down droids, willing to fight Kitt for "killing" one or running out into a war zone because she saw one that was "suffering."
Shadowgirls: Charon McKay, especially when she pulls the so-called Slayer of the Elder Gods that was manipulating her daughter out of her mind, with just her bare hands and kicks it in the face. Also Christmas Snow when she stabs the guy who's responsible for turning her daughter into an Elder God Avatar through the heart. And this guy was making fricking scary sea monsters afraid of him!
A far better example is Miranda Sinclair, an actual mother. The main protagonists usually have trouble facing a single demon in combat, even if they're fighting together. When Miranda's family is threatened, she single-handedly makes THREE of them look like FOOLS.
Sluggy Freelance: The actual animal variant appears. She will not, however, protect her cub from the local Killer Rabbit, and does as it says. Which happens to be letting said rabbit disguise itself as a cub, and then going around doing flagrantly criminal things, while people refuse to stop him for fear of angering what they thing is a protective mother bear. Subverted when it turns out that bear was a male, the cub was his girlfriend's, and she was rather ticked when she found out.
Something*Positive: When a scary clown tries to threaten PamGee, Aubrey responds by crushing his hand and threatening to break his jaw if he ever comes near her daughter again. Given Aubrey's general reputation, this also crosses over to Mugging the Monster.
Stand Still, Stay Silent: A literal case. An antagonistic magical entity surrounds itself with three zombified bears that act as guards. The biggest bear is apparently the mother of the two smaller ones, and is quite protective of them. She proves surprisingly passive when first approached, but when her sickly cub is harmed she flies into a homicidal rage.
Terinu: Melika raised the title character as her own son for eight years until he was torn from her by the Space Pirate that had originally found him as an infant. When she's finally reunited with him again after seven years, she's not only grateful to find him alive, she's more than willing to engage in prison breakouts and confrontation with armored Space Marines to keep from losing him again.
Melika: "Harm my cub and I'll paint this chamber with your entrails!"
Thespiphobia: Gwyneth could never be considered as a super sweet girl. Mikayla is even worse. However — if you mess with the theatre's techies, or Mikayla's inventions, be prepared to burn more mightily than fuse in Hell. Not that Gwyn is oblivious to her techies' shortcomings — she's just the only one allowed to deal repercussions.
Wigu has Romy Tinkle who, while a raging alcoholic in poor shape, was capable of getting the jump on and knocking out a ninja when her family was threatened by bounty hunters.
The Powder Keg Crowd that attacked her daughter