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Rabid Dove refs Juuzou Suzuya from Tokyo Ghoul

Shy Boi (Any)
My Hero Academia (the flavor text clearly hinted it's deku)

This item is an item referencing Akame Ga Kill. It is the character Esdeath! biggrin

Oh and speaking of Sword Art Online:
Gale Sniper + recolors is a SAO item. Specifically, Sharpshooting Gale Sniper is the canon color version.

Star Wars:
Interstellar Invaders and recolors

Galaxy Rebels and recolors + hood cutter

Cili Yandere is a "canon correct" recolor of murder daughter.

Silent Hill -
Code Geass -
FLCL
BioShock - Delta/Big Daddy Elizabeth
Colonel Sanders Colonel Spicy
Team Fortress 2 - Medic, Red Scout, Blu Scout, Blu Spy, Red Spy
Kingsmen - King's Agent
Hellraiser Box of Pleasure and pain
Sherlock - Detectiving Consultant, Nice Suit For Work Sherlock, Jumper Collection - John Watson, Victorian Boyfriend's Sherlock Holmes film, Burnt Toast Sherlock, Tourist Hat
Hannibal - Cruel Cliffanger, SDPlus Gaian Cannibal Spirit Box, Someone Please Help me
Supernatural - Wayward Son Castiel, Hunted Ones Sam & Dean Winchester
Ghostrider - Ballad of Souls, Diablo Magnum

Effect Cosplay: Asari

"The View From Above" is a GundamW reference item.
"Mysterious Moon" and it's recolor for Escaflowne cosplays.

GDP Officer for Free! It might not look it at first glance, but it's a reference to Free! Eternal Summer's ending credits.

I also notice Gakkou Gurashi (School-Live!) and Zombieland Saga aren't on the list yet. Both are zombie anime series.
Gakkou Gurashi:
Survivor's Imagination for Yuki Takeya
Shovel the Dead for Kurumi Ebisuzawa

Zombieland Saga:
Forgotten Idols for Junko Konno and I think a hair cut item makes it for Ai Mizuno too.
Courtesan's Heart for Yugiri
Starstruck Sidepony for Sakura Minamoto Cutie Idol Cut for Lily Hoshikawa
Delinquent's Ponytail for Saki Nikaido
Terrible Tresses for Tae Yamada
There's also Bear-et from the Saga Styles item that the rest came from but I don't know who it's for.

The Sickest Pomp is a reference to Space Dandy!

Poco's udon world: Poco
Frog Obsession & Crystallized Frog Obsession, including the animal versions

KonoSuba (I think, I could be wrong though):
Royal Apprentice

Kaito from vocaloid. unknown version (he have different music videos so I forgot which version lols)

The Sickest Pomp is a reference to Space Dandy!

I found what appears to be Amethyst from Steven Universe!
gaiaonline.com/marketplace/itemdetail/10155977

I'm still on the search and keeping an eye out (especially for Fate related things ;;;0v0) ), but here are a couple of ones I know of.
Fate Series (More specifically, Fate/GO, Fate/Prototype, and Fate/Apocrypha)
FGO - Abigail
The Key (and recolours)
Fate/Prototype and Fate/Apocrypha
Knight of Winter's Solace (and recolours)

Elsword
Lord Knight Efficient Slayer (and recolours)

Goblin Slayer Series
Goblin Slayer - Body Guard (and recolours)

Might I make a suggestion? The Rubble Stockings item set is based on Black Rock Shooter. Might make a nice addition! I'd include more than just the name, but unfortunatly I don't know how to. Sorry! sweatdrop

Here is an item that is useful for Fairy Tail cosplays! Mahou Men
And this one, for Lucy Heartfilia's signature hairstyle: Light Student Council Princess Style

I don't have the opportunity to link you right now, but the "rose revolution" items sets are just one of at least two cosplay items for an older anime called "revolutionary girl, utena".

The name of the second item, which would have predated the rose revolution items, is unknown to me atm, but I know it exists because I had it once.

There may be other items.. Umm. "Rose saga" and its recolors are probably also a reference to the anime. Idk of there is one specific to the princess like for the main character, though.

I believe that Millennium Director is based on Paranoia Agent.

oh hello! Im really grateful that you made this forum but I saw The Undertale series isn't here.

I currently saw Muffet the spder baker; Ghastly Spider sweets (and its recolour) since it stated in the desc already.

Underworld Order too (and its recolour), one of the equips are similar to the game fighting screen.
disaster twins too because of the dialogue because some of the equip are referenced to the original game.

This is a reference to Sailor Moon R's Villan Ann and Alan (theres a blue set somewhere on gaia as well)

More Madoka Magica stuff: Make A Wish + recolors

From Chi's Sweet Home: Kitty's Playtime

Need help on this, i'm not sure myself..can someone confirm these? I think it's Lenneth from Valkyrie Profile. I was making a cosplay as her, and found these items along the way.
Here's a picture of Lenneth.

Valkyrie Profile:
Northern Valkyrie

Valkyrie's Descent

Valhalla's Eternal Armor
Valhalla's Obsidian Armor
Valhalla's Abyssal Armor
Valhalla's Gilded Armor
Valhalla's Undying Armor

I think this item is Tsumugi from Amaama to Inazuma,

Amaama to Inazuma
Goshiki Gluttonous Kit
+recolors

Gundam:
The View from Within |

Weightless Braid
Buoyant Braid

Fire Emblem Fates:
Basically everything from the style tactics 2 rig is a fire emblem fates hair or recolor of one.
list

(sorry there's a lot of stuff there to organize)
Stylin' all Night has persona items:
link
Tales of the Abyss

Guy Cecil
Devoted Swordsman Cut + recolors
Luke fon Fabre
False Heir Style - + recolors

Tales of Graces
Sophie -
Spirited Amnesiac + recolors +

Tales of Symphonia
Kratos Aurion
Mysterious Mercenary + recolors

Marta Lualdi
Flower of the Battlefield + recolors

Tales of Vesperia
Yuri Lowell
Handsome Vigilante + recolors

some corrections for your list (?)

under final fantasy you listed "Devoted Swordsman Cut", but it's not a FF item.
I dunno if is a reference recolor to alice ni kuni but it's from tales of series.

There are more tales of items (such as a Sheena hair from Symphonia) but I couldn't find it in the search... It's been too long since I searched for that. hope these help!

if you use agapes cut on "Reprobate Madman", it goes long, like in the game FF9

I don't know if any of these have been suggested already, but I didn't see them listed in the thread or guild.

Fire Emblem Awakening:
Nagashi Swordsmaster (Lon'qu)
Amnesiac Tactician (Robin)

Fire Emblem Fates:
Butler Maid For (Jacob + Felicia/Flora + Corrin's hair)
Fabric Family Issues (Keaton + Velouria)
Selken Favor (Kaden + Selkie)
Sleepy Servant's Style (Dwyer)

Fire Emblem Heroes:
High Queen of Heroes (Veronica)

Fire Emblem 3 Houses:
Progenitor Leader (Byleth + Edelgard)

Bravely Default:
Metamorphic Fairy (Airy)
Cheerful Bravery (Agnes + Edea)
Edebel (Edea + Ringabel)
Cunning Clyde (Ringabel/Red Mage)
Brave Bonnie (Edea/Spiritmaster)
Lestelle (Vampire)

Tales of Xillia
The Spirits Within (Milla)
Owari no Seraph
Peppiest Bloodsucker Around (Ferid)
Rose of Versailles
Rose Commander (Oscar)

Hello!
Morrigan from Darkstalkers has a few items on here!
Hair:

Item:

This is the closest of all the recolors and even includes the bats on her tights! The other recolors can fit too tbh

I have some few more list from my journal (not yet updated lately sweatdrop ) good thing I didn't erase it yet, I just didn't update it since I saw a much more complete list before.. but the entire list got erased crying (I won't be checking for the doubles sweatdrop )

[ANIME]
Amnesia - Tentative Heart - Ikki
Bakumatsu Rock - Ardent Idol Toshi
Bakumatsu Rock - Fervid Idol Toshi
Bakumatsu Rock - Vehement Idol Toshi
Cowboy Bebop - SDPlus Real S54 Uncle Kenny
DDMD - Digital Music Mystery Drama
DDMD - Without Rhyme or Reason ~~ kyaa!! emotion_kirakira whee
DragonBall - Head Case
Durararara - Dullahan's Edge
Flame of Recca - Path of the Orochi
Gakuen Babysitters - Teacher Teacher - 4 of the kids in the show xd
Haikyu!! - Volleynyan
Haikyu!! - I Scream - only the bangs up part sweatdrop - Coach Ukai
Magi - Game of Serendine
Maji 1000% - Starish
Noragami - Kofuku - Bad Luck Girlfriend
Noragami - Yato - Five Yen Favor
Naruto - Night Fright Skin
Neon Genesis Evangelion - Victoire Corsair
One Piece - Cookin for LOVE
Owari no Seraph - Seraph's Stalwart Devotion
Owari no Seraph - Simmering Seraph's Regret
Pokemon - Gacha Master
Pokemon - Sphere Sidekick
Sailormoon - Romantic Moonlight
Kimba the White Lion - Jungle King
Slayers - Namagomi the Abominable Priest
Slayers - Namagomi the Beastly Priest
Slayers - Namagomi the Destructive Priest
Slayers - Namagomi the Poisonous Priest
Soul Eater - Heartless One - Death the Kid
Space Dandy - Sweet Honey Waitress - Honey
Sword Art Online 2 - Gale Sniper - Kirito
Tokyo Ghoul - Indigo's Prophecy
Vocaloid - Vocal Headphones

[The Enigma Institute RIG]

Afterschool Treat Time - K-on!?
Cursed Student A - Mei Misaki - Another anime
Strangely Light Student H - Senjogahara Hitagi - Bakemonogatari
Energetic Student K - Shoyou Hinata - Haikyuu!
Peppery Pupil Student P - space dandy & ao haru ride?
Enigma Institute Student Uniform - Protagonists (Minato/Minako Arisato) - Persona 3
Lucky One - Nagito Komaeda & Clear- dangan ronpa & dramatical murder combined?
Magical Chiaroscuro - Monokuroma - Dangan Ronpa
Nimble Cyclist - Makishima Yuusuke - Yowamushi Pedal
Ouendan - Ryuuta Ippongi - Osu! Tatakae! Ouendan --------- game
Peppy Battle Bot - Penny - RWBY ------ cartoons
Popular Flirt - Mikoto Mikoshiba - Gekkan Shoujo Nozaki-kun
Protagonist's Choice - Yu Narukami - Persona 4 // Fire Emblem: Awakening // Persona 3 Kotone Shiomi, Minato Arisato
Secret Character J - Junko Enoshima - Dangan Ronpa
Secret Character M - Junko Enoshima - Dangan Ronpa
Secret Mangaka - Chiyo Sakura - Gekkan Shoujo Nozaki-kun
Seifuku Slicer - Satsuki Kiryūin // Ryuko Matoi // Mako Mankanshoku (Hair + Agape) - Kill la Kill
Senpai's Discipline - Gamagori Ira - Kill la Kill // Kiyotaka Ishimaru - Dangan Ronpa
Senpai's Order - Gamagori Ira - Kill la Kill // Kiyotaka Ishimaru - Dangan Ronpa
Silent Nurse - Silent Hill Nurse // Mikan Tsumiki - Dangan Ronpa 2

[CONspicuous List]
Human Items

Perona from One Piece - All Negative
Machenzie/ Shirou Tachi from Touch Detective - Double Mystery
Kashuu Kiyomitsu from Touken Ranbu - Fashionable Swordsman
Blue Version of Estelle's defualt costume from Tales of Vesperia - Flower of the Full Moon
Estelle's Heroic Actress costume from Tales of Vesperia - Stage Play Heroine
Tate and Liza from Pokemon ORAS - Inner Strength
Pearl/Opal from Steven Universe - Iridescent Matron
Iris Watson from Phoenix Wright: Ace Attorney - Little Miss Detective
Crow from Fragile dreams - Memory of a Corvus
Going Merry from One Piece - Merri Going
Lina Inverse(top)/Xellos/Filia UI Copt(tail) from Slayers - Namagomi the Beastly Priest
Aurora/Igniculus from Child of Light - Petite Lumiere
Protagonist from Persona 5 - Shadow Thief
Super Sonico from Super Sonico - Super Guradoru Singer
Amethyst/Opal from Steven Universe - Violaceous Aegis
Aqua from Fire Emblem If - Wartorn Dancer

Sdplus Doll
SDPlus #563 Goth Murasaki - Suigintou from Rozen Maiden
SDPlus #564 Batter O. Renji - Ren Mihashi(hair) from Big Windup and Seidou Uniform from Ace of Diamond
SDPlus #565 Super Takkun - Gohan from Dragonball Z
SDPlus #566 Idol Alleycat - IA from Vocaloid

Animal Items
[Animal] Let's Go Exploring - Calvin and Hobbes from Calvin and Hobbes
[Animal]Little Miss Detective - Iris Watson from Phoenix Wright: Ace Attorney
==================================
[GAMES]
BlazBlue - Quarter Fighter
Dangan Ronpa 2 - Super Level Academy
Chrono Cross - Chronomantique Jester
FFVII - One Winged Soldier - Sephiroth & or Angel of Death - One-Winged Death God - Yuda from Samurai Showdown: Warrior's Rage http://snk.wikia.com/wiki/Yuda]
FF - Ultimate Roundball Punch
FF - Unlikely Hero
FFVII - The Charming Mr. Dorian - Sephiroth
FFVII - Good at Being Bad - Tifa
FFVII - One Winged Angel
FFVII - One Winged Fighter
FFVII - One Winged Soldier
FFVIII - Artificial Love Song - Rinoa?
FFVIII - Disorganized Hero - Squall
Hatofowl - Hatofowl
King of Fighters? - Mao's Hachimaki
Persona 5 - Shadow Thief

[Fantasy Flare II Bundle]

Dark Mysterious Conjuring Braids - FFX - lulu
Cool or Warm Reprobate Mad Man Feathered Locks - FFIX - Kuja
Dark Stolen Memories Spiky Hair - FFVIII - Zack Fair
Eclectic Lapin - FFXII - Fran
Dark Final Ruler's Hair - FFXV - Noctis Lucis Caelum
===================================
[CARTOONS]
Beastly Professor - Beast from X-men
Plumber's Belt - Super Mario
Risky Angels - Panty and Stockings Garterbelt
Tendril of the Ocean - Little Mermaid - Ursula
===================================
[Others]
Enforcer Officer - Robocop
Babewatch - beverly hills 90210 beachwatch??
Comics - Anti Hero Possessions
Comics - Prized Possessions
Comics - 90's Comic Book Hero!
Captain America - Supernatural Arsenal
Captain America - Captain America's Shield
Batman - Durem Knight

== Pure Pawsplay RIG ==
[Animal] Data Dog (Animal) - DDMD
[Animal] Spiral Sol (Animal) - Cardcaptor Sakura - Spinnel
~~~~~

hello! i don't THINK i saw it listed, but princess of the world (and variants) is a vocaloid reference to this song!

i believe tactician of the world and variants MAY also be vocaloid references, but i couldn't find any songs/media with similar designs so it may just be gaia playing off of their own design. i think the whole chess series thing is all gaia anyways

there's also the male version of the item, prince of the world (and variants again) but i'm not sure if it'd count, since the design seems to be entirely gaia playing off of the princess of the world design again and not official vocaloid

EDIT: the video has it in there, but just in case, here's a ref pic of a frame where miku is posing in the same way as the item (and is also wearing a very similar outfit + the same hair)

I posted this on the thread but I'm also going to post it here with another one I found:
Kaguya-sama Wants to be Confessed To:
Bowtiful Chica

Yuru Camp△: (I'm not really sure since I haven't watch the anime, but the items fit the description though.)
Cozy Camping
Classic Cozy Camping
Lucky DishSarazanmai

Hi! Do you have any items for the video game Bravely Default?
edit: saw the items on the previous page on someone's suggestions. I'd also like to add the Fairy Grave items.
Fairy Grave

Fairy Tomb
The hair clip item is very similar to the Summoning job's icon and the hair clip of the actual Summoner class (picture here), I think this item is based on how Venus, a boss of the game, kills fairies.