The Magical Girl genre is one of the staple genres of anime and manga. It has existed in one form or another since almost the beginning of modern day animenote and has continued to be popular throughout the decades. It's gotten to the point where many non-Japanese works, such as W.I.T.C.H. and Winx Club, are based on Magical Girls.
As a result of the success of the genre, spinoff works or skits aren't rare where characters are turned into magical girls. Even if they're boys, they turn into magical girls. Maybe it's All Just a Dream, maybe it's an outright Alternate Universe, but for whatever reason the characters in a work are suddenly transformed into magical girls.
Most of these AUs are very tongue-in-cheek or are outright magical girl parodies. Magical Girl tropes are usually exaggerated as a result. The protagonist will become a Pink Heroine in Frills of Justice who screams out her attacks and fights against a Monster of the Week. Though most magical girl AUs are light and comedic, some works do take it seriously. Many take inspiration from either Sailor Moon or Pretty Cure, though more obscure references and nondescript pastiches of magical works are also commonplace.
If this AU appears in non-Japanese works, expect it to be a parody (often a Shallow Parody) of Sailor Moon. Though numerous magical girl anime have been dubbed outside of Japan, the only one to strike out of the Girl-Show Ghetto and become mainstream was the 1990s Sailor Moon anime. As a result, any magical girl anime tends to be called a "Sailor Moon ripoff" by non-magical girl fans and especially non-anime fans.
- Sayonara, Zetsubou-Sensei had a bit where characters turned into Lily Cure and Itoshiki was the Big Bad.
- There has a Nisekoi Magical Girl spinoff called Magical Patissier Kosaki-chan. It stars Kosaki, Chitoge, and Marika as magical girls.
- Lyrical Nanoha is the once-removed More Popular Spinoff of an adult visual novel series called Triangle Heart 3: Sweet Songs Forever:
- In the original VN, Nanoha appeared as a minor character, being the Adorably Precocious Child little sister of protagonist Kyouya Takamachi. The accompanying fandisc Lyrical Toybox would give her A Day in the Limelight, making her the star of a short Parody scenario called "Magical Girl Lyrical Nanoha" where she received Magical Girl powers from a fairy called Lindy in order to fight a boy named Chrono.
- This story would later be adapted into the anime Magical Girl Lyrical Nanoha, which changed many things heavily (including Nanoha's original Magical Girl outfit becoming her school uniform, and Lindy and Chrono becoming human members of the Time-Space Administration Bureau who assist her). Most characters from Triangle Heart are reduced to Mythology Gag cameos with no supernatural elements and fade into the background quickly, while the role of Kuon is split into a pair of new characters, Yuuno and Arf. Partway through development, it was noted that Nanoha's sleeves looked like something out of Gundam, and thus was born a Magitek Magical Girl Warrior series with gratuitous references to automobiles and Super Robot Wars. Weirdly, the story actually drops back out of the Magical Girl genre as time goes on, with the third season having Nanoha grow up and command a unit of military wizards in another dimension.
- Black Lagoon had an OVA Alternate Universe that turned Revy into a magical girl called "Radical Girl Revy-Chan". She solves all her problems with guns before returning to the magical land of Hestonworld. This gets Rock arrested.
- In the High School A.U. of Kino's Journey, Gakuen Kino , Kino becomes a magical girl at one point.
- One of the Higurashi: When They Cry OVAs had Rika transform into a magical girl. The OVA is noticeably Lighter and Softer, Denser and Wackier, and more fanservicey than the normally dark and bloody series.
- Pretty Sammy and Sasami: Magical Girls Club are both magical-girl-based spinoffs of Tenchi Muyo! focusing on Sasami.
- Fate/kaleid liner PRISMA☆ILLYA is a spinoff of Fate/stay night that turns Illyasviel von Einzbern into a magical girl that uses card-based transformations to gain the powers of Heroic Spirits. Fate/stay night had a fourth route for Illya that was scrapped in development, with its remaining elements being folded into Part 3. While Prisma Illya is an Alternate Universe story and often silly, it gradually introduces elements that directly continue on from the themes at the end of the original story, and Kinoko Nasu has even said in interviews that it is the Illya route.
- In Demashita! Powerpuff Girls Z, the titular girls from The Powerpuff Girls are given counterparts who are Magical Girls. It's a variant as the Z Powerpuff Girls aren't exactly the same characters, but able to transform into a form resembling the original Powerpuff Girls. The original Powerpuff Girls was a magical girl (and superhero) parody but the anime version plays the genre straight.
- The Grisaia Series has a spinoff called Idol Mahou Shoujo: Chiruchiru Michiru where Michiru is a Magic Idol Singer.
- Senki Zesshou Symphogear has the in-universe magical girl series Kaiketsu*Utazukin! (a parody of Akazukin Chacha) created to cover up the heroes' activities, with its protagonist implied to be based on Chris. While Symphogear itself only skirts the edges of Magical Girl Warrior (the protagonists being teenage and early-20s government agents in Powered Armor), Utazukin is presented as an old-school Cute Witch story, albeit one with a bizarre plot.
- Parodied in My Monster Secret. Akane created the Show Within a Show The Middle Aged Magical Girl, Magical Akalyn, basing it on Christmas Cake Akari's inability to get any guys. Akari isn't really pleased when she found out.
- Super Doll★Licca-chan is for all essences a Magical Girl Animated Adaptation of the Licca-chan toy line. In it, Licca is actually royalty. She uses three magical dolls to thwart the main villain.
- Dolphin Rider Koishi is a High School A.U. Touhou Fan Fic starring a human version of Koishi Komeiji as a magical girl who rides a dolphin approximately once. Notable for not being a Parody or Darker and Edgier but played completely straight, being an idealistic story about Koishi helping the Woobie of the Week to get over deep-seated psychological issues.
- Friendship Is Magical Girls is a High School A.U. of My Little Pony: Friendship Is Magic featuring human versions of the characters living in a fictional stand-in of Japan, with the Mane Six being chosen as Magical Girl heroines.
- Lux-Umbra Magna Auguratricis serves as one of this for The Loud House. In it, the Loud sisters are turned into magical girl warriors in order to combat evil creatures simply known as Shadows.
- B K Willis's Sailor Who is a Meta Fic with Doctor Who companions (Susan, Leela, Zoe and Nyssa) plus the author's genderswapped avatar trying, and failing, to keep in character as Sailor Scouts.
- The Star Guardian skins of League of Legends. It first started with Lux and was treated as just a parody of Sailor Moon. It wasn't until skins of Jinx, Poppy, Janna, and Lulu came out that a backstory was established for the group.
- Heroes of the Storm gives Li-Ming a skin inspired by Sailor Moon, "Star Princess Li-Ming". There's also a spray that depicts Chromie as a Cute Witch-style magical girl.
- Honkai Impact 3rd: Theresa (as one of her "Valkyrie Suits", Sakuno Rondo) has a magical girl-inspired alternate costume, as well as a special rare weapon that goes with it, designed like a Magic Staff (but is still used like the mechanical crosses she usually uses). The Flavor Text for said weapon is a Shout-Out to Fate/kaleid liner PRISMA☆ILLYA, too.