Monsters exist all over folklore. Dragons, vampires, werewolves, etc. And usually, they start out as Always Chaotic Evil as they come, or even just mindless beasts who destroy because they don't know any better.
Except, as a particular monster gets more popular, it has a tendency to get less... monstrous. Dragons (which at least in Western mythology were once giant, winged, fire-breathing lizards that burned villages and were slain by knights) first got more intelligent, then more likely to be a "not really a monster" subversion, until, in the modern era, stuff like Dragonheart and Pete's Dragon are nothing to bat an eye at. Similarly, orcs - who were invented for The Lord of the Rings to be bred evil (and mostly stupid) often appear as "noble savages" after just eighty years.
There are also cases where said monster is modified in order to appeal to younger demographics (and otakus) by making him (or her) more cute, huggable, and so forth.
In short, this trope is Villain Decay on the species level - what happens when Our Monsters Are Different turns the exception into the rule. Criticism of the Always Chaotic Evil trope may also play a role.
See also Adorable Abomination, Cute Monster Girl, You Sexy Beast, Lovecraft Lite, Disneyfication. Friendly Neighbourhood Vampire is a subtrope of this. Did We Just Have Tea with Cthulhu? can lead to this effect if done often enough. Not to Be Confused with the plot of Despicable Me.
To avoid ranting, examples list should only be those contained to be a single franchise or canon:
- Regarding dark elves:
- The heroic dark elf Drizzt Do'Urden in The Legend of Drizzt has fast-tracked the taming of his race in Dungeons & Dragons, where they're also known as drow. The race was still mostly evil, but the template of the Chaotic Good renegade dark elf became an Overused Copycat Character by now, even though the archetypal Drizzt himself was more unique when first introduced because good drow were way less common back then. In 2020, Wizards of the Coast would introduce several new non-evil Drow cultures, putting them further into this territory
. An article titled Diversity and Dungeons & Dragons has more details about newer depictions of Drow.
- Untaming the grue is very much in mind with drow in Pathfinder. The drow of that setting are fleshwarping, demon-loving complete monsters who tried to crash an asteroid into the surface in order to bring about a second age of darkness and destroy any resistance to enslaving the surface dwellers. They would have gotten away with it if it wasn't for those damn player characters.
- Dwarfs in Norse Mythology may have conceptually evolved from dark elves; indeed, the Prose Edda equated dwarfs with dökkálfar and svartálfar (literally "dark elves" and "black elves" in Old Norse, respectively). As such, you'd expect these guys to be pretty depraved, and they often were in the myths. But as time went on, they became shorter and less malevolent until they were recognizable as the dwarves (spelled with a v, following J. R. R. Tolkien's example) that we know and love today.
- The heroic dark elf Drizzt Do'Urden in The Legend of Drizzt has fast-tracked the taming of his race in Dungeons & Dragons, where they're also known as drow. The race was still mostly evil, but the template of the Chaotic Good renegade dark elf became an Overused Copycat Character by now, even though the archetypal Drizzt himself was more unique when first introduced because good drow were way less common back then. In 2020, Wizards of the Coast would introduce several new non-evil Drow cultures, putting them further into this territory
- Elves and fairies in general have gone from The Fair Folk to often Always Lawful Good over the course of modern history.
- Godzilla began as a horrible monster and nuclear bomb metaphor. Later on he became a protector from other monsters, to the point of being unambiguously heroic during The '60s and The '70s, before being re-tooled as a different kind of nuclear bomb metaphor: still a defender, but one you don't want to have to use.
- As of the mid-2010s, however, two very disparate depictions of Godzilla popped up in modern culture: the American Godzilla (2014) that portrays him as a noble anti-hero who represents nature's order, and Japan's Shin Godzilla that portrays him as a horrific abomination against nature that man unleashed onto themselves. Strangely, either depiction isn't really unfaithful to the "returning to the darker roots" concept that both films advertised.
- The Kaiju genre, of which Godzilla and King Kong are the most prominent examples, are subject to this.
- Pacific Rim provides an in-universe depiction. Kaiju, once as deadly as natural disasters, are kept in check thanks to the Jaeger program. For most people, kaiju go from a terrifying threat to a distant annoyance, and humanity acclimates to their presence. A quick montage depicts kaiju re-branded as mascots, spiritual icons and kid-friendly cartoons (much as they have been in Real Life).
- There are Cthulhu plushie dolls (as shown in the page image). Not to mention Hounds of Tindalos, gugs, Mi-Go. Moreover, recent fiction is much more likely to play these guys for laughs rather than straight. In a sense, it was bound to happen: H. P. Lovecraft's works played heavily on the fear of the alien and unknown. His works becoming Household Names, meaning that now everyone knows about them, ironically defused their entire point.
- In-universe example for Sam & Max: The Devil's Playhouse. Turns out that back near the beginning of our planet's existence, molemen were powerful, destructive creatures who could successfully fend off Eldritch Abominations. They didn't evolve well.
- Werewolves have this problem, on and off. Old folklore describes them as vicious animals, at best, but contemporary works tend to humanize them more. They still get cast as vicious animals, but their humanity is still more pronounced. Some traditions have werewolves as a type of witch who sold their soul for their ability to transform, so even as human beings they were evil. Modern werewolves tend to either be innocents who contracted the curse by being the victim of another werewolf, or having been born that way (and usually possessing some degree of control). Either way, they can't help what they are. The softening of the Werewolf dates back as the 12th Century where Marie de France writes the tale of the Bisclavret who was trapped in his Wolf form by a treacherous wife after revealing his secret and is captured then kept as a pet by the King who he remains loyal to, even as a Wolf.
- Vampires can be more or less human, and more or less hostile to non-undead, depending on the writer. In recent times, with growing popularity of Vampires Are Sex Gods, they've gotten a bit softer. See Friendly Neighbourhood Vampire.
- As the torch-bearer of vampire fiction, Dracula has been hit especially hard by this, with most modern depictions and cameos (almost always using Bela Lugosi as their main reference, accent and all) either deliberately making him more sympathetic or turning him into a joke for the heroes (or the real villains) to run rings around. Even the modern adaptations/pastiches/etc. that do try to play him as a straightforward monster usually can't do it without some level of self-aware Camp.
- The Trope Namer, grues, first appeared in Infocom's classic Zork games as the unseen (and, because they never leave pitch-dark areas, unseeable) monsters who would eat adventurers careless enough to wander in dark places without a light source. Later works such as Wishbringer and Zork: The Undiscovered Underground would play grues for laughs; Wishbringer featured a grue lair with a refrigerator whose light goes out when you open it and a mother grue with an apron, while Undiscovered Underground had a grue convention where grues would discuss topics such as 'Surviving the lean years'. The grues were still dangerous, but played less seriously than in earlier works. Somewhere in between was Ancient Domains of Mystery's treatment of grues, which made them killable monsters — played seriously aside from the Shout-Out aspect but less formidable than an unseen, unbeatable threat. The once-popular humorous wiki Uncyclopedia pokes fun at grues even more, making them look like the weird Japanese character Domo-kun for the hell of it.
- Zombies and Skeletons: while never portrayed as cute or cuddly (most of the time), in cartoons it's not uncommon to see Friendly Zombies and Skeletons, who can detach and attach their parts at will. Then there are movies such as Hotel Transylvania, Daddy, I'm a Zombie and Corpse Bride (In which the undead were much more lively and upbeat than the extremely dreary land of the living) and of course the Monster High franchise. Even then there are fantasy novels and videogames which may feature Zombies who are friendly but either wish to be accepted by humans, or wish to die due to seeing themselves as monsters. Subverted in Fallout in which the "Zombies" aren't actually zombies (And don't use that word in front of them) but are humans mutated by radiation to look like a corpse, but if their brain become radiated enough they can become "feral" and act like typical zombies.
- Over the course of the franchise the Velociraptors in the Jurassic Park movies got this treatment. They were outright villains in the first two movies, but got a slight Anti-Villain treatment the third. By the time Jurassic World came out, they were treated more as anti-heroes, and one, named Blue, was a straight-up hero.
- Rexy the Tyrannosaurus rex has also been hit with this. In the original novel, she was very much an antagonist, relentlessly hunting down Alan Grant and the children to the point of leaving behind a dinosaur she'd just killed when she noticed they were nearby. She got a similar treatment in the first movie, and the fact that she saves them from the raptors is treated more as a lucky coincidence than anything else. Come Jurassic World, she's deliberately used to defeat the Indominus Rex, and in Jurassic World: Fallen Kingdom she once again returns to eat the human villain, while leaving the heroes alone.
- In Prince Caspian, Bacchus and the Maenads undergo this treatment. The original Greco-Roman myths depict Bacchus as a fearsome god of alcohol and madness, and the Maenads as frenzied cultists who partake in orgies of ecstasy and gruesome violence akin to The Wild Hunt. In Prince Caspian, on the other hand, Bacchus is almost like the Disney version of Peter Pan, and the Maenads are the female equivalents of the Lost Boys. To someone versed in Classical Mythology, this comes off like a kiddie cartoon called "Mola Ram and Friends." This is somewhat justified in-story by the implication that they're changed by Aslan's presence, losing the aspects of their character associated with corruption and becoming representatives of harmless joy and high spirits. Susan even comments that "I wouldn't have felt very safe with Bacchus and all his wild girls if we'd met them without Aslan." It's a clear reference to the Christian "baptism" of pagan symbolism (e.g., the use of pre-Christian Germanic traditions at Christmas).
- Upon reading an early draft of The Lion, the Witch, and the Wardrobe, Lewis' good friend J. R. R. Tolkien apparently felt this way about Mr. Tumnus, commenting to a third party that a myth-accurate satyr would have done more to Lucy than give her tea.
- In their original appearance in the Disney Ducks Comic Universe, the Terra-Firmians were sociopathic subterranean savages who cared not a whit about the massive destruction and loss of life their rolling competitions caused on the surface. Their appearance in DuckTales (1987) was much softer, with the Terra-Firmians being much less monolithic in their self-absorption. Then comes DuckTales (2017), where they're practically cuddly — they're just plain folks who live underground, look like rocks, and occasionally come up toward the surface to explore.
