Interesting Monster High design things that are never explicitly stated:
* Unlicensed vampires are all some type of pink-skinned for some reason, including related species like the manananggal
* Clawdeen, and by extension, other werewolves, never wear silver metals, because that weakens them. The Wolfs only wear gold jewelry and accents.
* Lagoona's sporty theme aligns with the use of mesh fabrics to make a pun about fishnets
* Wydowna Spider's hairline is a widow's peak and one of her hands is in Spider-Man's web-slinging shape
* Twyla's eyes glow in the dark on most editions--common knowledge, but Mattel has never told buyers about it on her boxes!
* Twyla is a boogeyman and her costume designs all feature antique architectural details and imagery of things that might be in a scary bedroom at night, like wallpaper patterns, doorknobs, bugs, and beds, while her outfits often resemble pajamas
* The two G1 pop star characters are a witch and a black cat, and a witch and cat were also a Create-A-Monster duo
* The Grant sisters' monster twist on genies is to make them plated like desert scorpions
* Elissabat's face is deliberately highly similar to Draculaura's, but their sculpts have been determined to be different--this when MH has used shared sculpts for more distant-looking and disparate pairs of characters!
* The Blob and Ice Girls are a Create-A-Monster duo because freezing was the one weakness of the Blob monster
* Deuce and Cleo as a couple invoke the synergy of snakes and Egyptian culture, the famous Cleopatra being Greek, and Cleopatra being stated in legend to have died by snakebite--similar reasons a mummy and Gorgon were paired in the Create-A-Monster sets
* Operetta is from New Orleans because it's a uniquely French area of the USA, tying her into the original setting of the Phantom of the Opera
* Viperine Gorgon has distinct visual hallmarks of both human and serpent albinism, and her use of sunglasses could correspond with sensitive eyes from the condition, though she's never stated to have the condition in any material.
* Great Scarrier Reef's transformations: Electric-powered Frankie became an electric eel, Draculaura became a vampire squid, and tigerlike Toralei became a lionfish. I've heard Clawdeen was based on a wolffish, but can't be sure that was actually clear. Gil turning into a ray may be a pun with manta and manster? No idea if Lagoona was based on a specific fish or not. Nor why she even had to transform in her native territory for any reason beyond making a new doll.
* Bonita Femur's color palette is based on the rosy maple moth, which is as implausibly candy-colored as Bonita. Luna Mothews is absolutely not actually a luna moth, but could be loosely based on the cecropia moth, the largest in North America and found in regions that could include New Jersey where she and the Mothman are from. Her yellow exoskeleton also loosely resembles the hornet moth, but may not intentionally be based on it.
* Mouscedes King, Luna Mothews, and Elle Eedee are a primary yellow/red/blue trio but also a past/present/future trio based on an old fairy tale, a current cryptid legend, and a speculative idea of future tech
* Headmistress Bloodgood's first name was eventually revealed to be Nora, an iconically Irish name that may have been chosen to liken Bloodgood to the Irish folklore of the dullahan, another "headless rider" monster.
* River Styxx is a young-adolescent Grim Reaper ghost who is partially translucent, revealing bones in her limbs and having a more opaque face that looks like thin skin over a bony structure. This creates a fun possible worldbuilding idea that reapers start as ghosts with skin and it fades as they develop, becoming full skeletons in classic Death style when mature.
* Peri and Pearl are conjoined Hydra sisters, obviously reflecting a rare human scenario of conjoined twins through the Hydra monster concept, but also possibly being influenced by the animal phenomenon of snakes being born with two heads in an even Y-shaped structure.
* Elle has a separate sculpted panel on her hip where her factory stamp is placed, canonizing the real-world manufacturing artifact as a real/literal/diegetic feature on the manufactured robot character.
* Corazón Marikit's red fringe blends the two halves of her outfit, but also stands in for the gorier imagery of dangling intestines and entrails when the manananggal monster's body splits at the waist. She does have a spine coming out of her upper torso as the peg that clicks her pieces together, but the dolls aren't brutally gory, so her costume alludes to the folklore's more extreme imagery in a graceful way.
