—Description of Croix Meridies from Witchpedia.
—Croix Meridies, Chariot and Croix
Croix Meridies (クロワ・メリディエス Kurowa Meridiesu ) is the main antagonist of the Little Witch Academia anime. She is the new teacher of Modern Magic in Luna Nova Magical Academy and an old best friend of Ursula.
Croix is a young woman of tall stature with a pale skin complexion. Her eyes are a greenish shade of teal. She paints her eyelids with pink eyeshadow. Her short, lavander hair has a wavy hairstyle, with a lock that usually covers her left eye.
She wears a red, gray and white suit that covers most of her body, with a lapel that reaches the height of her ears. She has a brown leather saddlebag. In the same colors as her suit, she also wears a large red cape and high-heeled boots. Sometimes she wears purple-rimmed sunglasses.
As a student, Croix's hair was significantly longer and she wore eyeglasses, in somewhat of an inversion of Chariot's (whose hair was originally short and later started wearing glasses) disguise as Ursula. She also usually wore sweatshirts. Unlike Chariot, however, Croix kept her original hair color.
After the Noir Rod missile was destroyed, Croix left her hair down, similar to how it was when she was younger. She started wearing a taupe full-sleeved shirt, brown pants, and a tan cloak with burgundy stripes worn over her shirt. Under the taupe, she wears a plain black shirt. She also no longer paints her eyes with eyeshadow. In this sense, she looks very plain and removed from magic in its entirety.
In her youth, Croix was a timid and reserved child who was known as a prodigy for her academic excellence. She also used to be a kind and considerate friend of Chariot du Nord, the charming and talented witch with poor proficiency in academics and a tendency to make blunders. Beneath this exterior, Croix held a great dream to become the world's greatest witch that would result in her being chosen by Claiomh Solais' power so that she could obtain the World Reconstruction Magic. Therefore, her efforts in her studies were singularly focused on it.
Croix changed upon seeing the power choose Chariot instead. She then rejected Chariot, becoming bitter, selfish, cold and calculating as her biggest dream ended up in her best friend's hands against her wishes. Although she initially set aside her resentments, Croix could never shake the envy towards Chariot, especially upon seeing her not taking her quest for the Seven Words of Arcturus seriously. The increasing frustration and envy ultimately caused her to forcefully play her role in her stead by bypassing the traditional ways of opening the Grand Triskellion, even if it meant she had to betray Chariot by tricking her to employ Dream Fuel Spirit on innocent audiences including young Akko and Diana as part of the said scheme.
After her separation and eventual falling out with Chariot, Croix had delved so deeply into the darkness that she became a highly logical but deeply ruthless, vengeful, ambitious, and cold-hearted person who hid her worst traits underneath her charismatic and cool persona. She doesn't take the welfare of the many innocent people who become part of her "experiments" into account, and this has made her commit a number of fairly horrific deeds, such as nearly ruining the bonds between Akko and Chariot, harming innocent people, and coming close to sparking a potential all-out war between England and its rival nation just to activate her Noir Rod; all of which she did without any signs of hesitation or remorse; she didn't even hesitate to kill or at least demoralize those who stood in her way either.
Despite how different her adult personality seemed, traces of goodness within Croix's heart still remained. Even with how far she had fallen, in "Wagandea", Croix was shown genuinely panicking when her robots made Chariot fall unconscious on her broom and nearly plummet to her death, and Croix's cries to awaken Chariot saved her life and let her chase Akko while her Magitronics were ready to fight again. Also, in "The Road to Arcturus", when Woodward confronted Croix after she broke the seal of Grand Triskellion and found that what she sought for is not what she wanted, Croix unleashed her anger and called Woodward out for what went wrong in the past and not helping her cope with the Shiny Rod's rejection. After this, Chariot helped save Croix's life from her own beast, even though Croix wanted Chariot to save herself and let her die by it's hands.
Croix can remain uncannily cool under pressure no matter the situation. She also proves to be a very intelligent strategist as well as an expert manipulator who meticulously devises many safeguards and people to ensure that things go in the direction she wants them to. Even when it seems things might not go quite how she's planned, she is confident that even Chariot is powerless to stop her nefarious plot to obtain the magic of the Grand Triskellion. True to this, she pioneered in the field of Magitronics, having surveyed Akko for months before revealing herself. Croix was also responsible for planning the fairy staffs' strike as she infiltrated Luna Nova by posing as a new teacher, lulling all of the campus' inhabitants into a false sense of security, commencing the chaos at Appleton Academy so she could take a sample of the rage-based Fuel Spirit from one of the witch-hating students there to confirm whether anger produces more power by being processed into the Fuel Spirit, she instigated attacks during the Wild Hunt, attempting to murder by exposing Akko to Wagandea pollen, and harvested anger from the strike over the soccer verdict. However, her inability to see possible flaws in her plan in harvesting anger-based Fuel Spirit energy and fathom that things she sought might not end up like what she wanted ultimately caused the witch's undoing.
Towards the end of the series, Croix, having comes full circle from being the first person to espouse the importance of believing in one's magic to being reminded firsthand of why such sentiment was correct all along, eventually reverted to her original kind and considerate self, promising to Chariot to find the way to break Wagandea's curse as the first step of her atonement.
Abilities and Equipment
Possessing advanced knowledge over technology and magic, Croix has developed several mechanical inventions through merging both concepts into a technique called "Magitronics". While a skilled witch herself, Croix generally prefers to use her Magitronic devices over casting magic and when she does, it is often through Magitronic mediums such as tablet. During her time as a student of Luna Nova, she was recognized as a prodigy, although she was never able to match Chariot in her magical power, let alone impressing Finnelan due to the strict teacher's distate towards modern technology she implemented into her works.
Her traditional uses of magic on the other hand, include the creation of powerful sentinel statues guarding her lab, endowing blessed robes for protection, and memory erasure of a large group of people.
One of Croix's inventions is a roomba-like magitronic device called Sorcery Unit, which she described as "evolved" Magic Broom. In addition of enough strength to support a human being and withstanding blows, this equipment is designed with many functions, among which holographic projection, built-in weapons, and storing Pixels. Like roomba it based on, Sorcery Unit can clean floors.
Floating cube-like devices that capable of absorbing emotional energy from people and convert it into magical power through a process called Noir Fuel Spirit. They can combine into different monsters under Croix's control as well as possessing objects to control them.
Smart devices designed to interact with and control the different magitronic devices. Croix can cast spells through them and uses them to teach her students during her time as Modern Magic Teacher.
The massive, magitronic replica of Shiny Rod that can transform into different configurations and powered by negative emotion-based Fuel Spirit via. Pixels that make up some parts of it. It is also designed with enough power to undo the seal of the Nine Olde Witches in which Grand Triskellion was kept, but the amount of negative emotion-based Fuel Spirit resulted it not only eventually developed a sentience and turned against her, but also corrupted its programming that it eventually breaks free from her control and aimed to destroy the world.
A device that designed to absorb the excess magical energy radiated by the Sorcerer's Stone from the Ley Lines that would normally go to waste and convert it into a form which is more storable, maintainable and efficient, allowing a much greater and more efficient magic energy reserve. If several of Sorcery Solution Systems are active at the same time, it allows a much greater magical energy reserve that is also transportable.
An app which enables Croix to harvest people's negative emotion-based Fuel Spirit on a bigger scale.
- The monster that appears during Shiny Chariot's magic show in the flashback at the beginning of the first episode resembles Croix's magitronic devices closely and makes the same sound before it materializes. It's later confirmed in Yesterday that the monster was a form of living construct Croix made from her magitronic cube seemingly used as part of Chariot's show, but in truth was to absorb some of Dream Fuel Spirit from audience as part of her plan to break the seal of Grand Triskellion in her own way.
- The design of Croix's younger self resembles that of a scrapped character named Elizabeth who originally intended to appear in the short films, and thus may very well based on the latter as well.
- Croix's name in the English dub is pronounced as "Croy", but in most other dubs it is pronounced "Cwa".
- In some ways, Croix's character is depicted as both foal and dark reflection of Diana Cavendish. Croix and Diana are both rivals and friends of bearers of Shiny Rod, both of them wished to be chosen as the bearer of Shiny Rod only for the Rod to choose their friend/rival. Croix was dismayed that Shiny Rod chose Chariot over her, Diana was similarly upset upon finding out that Akko had become the current bearer of Shiny Rod after learning the Rod's true nature and purpose. They are also very frustrated at the current bearers of the rod's lack of interest in their duty to restore magic. However, whereas Diana starts as a rival to Akko but develops a friendship with her over time, and her intention to gain Shiny Rod was for a noble cause; Croix starts as a friend but develops a strong envy against Chariot, proceeds to forcefully play her role in her stead by bypassing the traditional ways of opening the Grand Triskelion, and just wanted to be the world's greatest witch.
- Croix's favorite food happens to be ramen, which coincidentally, ties to her seiyuu's more famous role as Naruto Uzumaki from the Naruto series.
- Like Naruto, Croix' motivations (a dream to become something famous), prior foil-based rivalry based on a prior-friendship, neglect by someone else in the past and her achievements based solely on her efforts are eerily similar to his albeit on a flipped scale; Naruto remains true to his beliefs and dreams where as Croix has retained her jealously and resentment of being unacknowledged by Woodward.
- Croix however, is much more in common with Jugglus Juggler, antagonist-turned-antihero from Ultra Series for following reasons:
- Both of them were rejected by an artifact of great power they sought in favor of their best friend (Shiny Rod/Claiomh Solais rejected Croix in favor of Ursula/Chariot while Halo of Light prevented Juggler from reaching Orb Calibur within but allowed Gai instead). Interestingly, the manner said artifact rejected them eerily similar (electrical energy shock).
- Both of them initially put aside their resentment toward their said best friend until an unfortunate turn of events pitted them against one another as fierce rivals (Croix lost her faith in Ursula/Chariot during their struggle to unlock the Final Word to no avail and plagued by anguish over the uncertainty regarding the future of magic in the world while Juggler similarly denounced his support for Gai after his perception regarding true justice the latter believed in shattered by the conflict between War Deity and Queen Bezelb).
- Both possesses a dark counterpart of their respective rival's iconic item (Noir Rod (magitronic replica of Shiny Rod) for Croix and Dark Ring (darker counterpart of Orb Ring) for Juggler).
- Both eventually redeemed themselves by joining forces with their rivals in combating a great threat they ironically released to the world (Croix assists Ursula/Chariot along with Akko and co. in combating Noir Rod she initially created to break the seal of Grand Triskellion at Arcturus Tower while Juggler eventually assisted Gai/Ultraman Orb in defeating Maga-Orochi/Magata-no-Orochi he initially unleashed to prove his point that darkness being the only thing that was eternal in everyone in the universe).
- As revealed by Yō Yoshinari in a Little Witch Academia-related AMA event, Croix indeed being sent into a jail for troubles she caused and occasionally visited by Ursula who brought her some cakes she baked herself. 
- Her first name, "Croix", taken from "Croix du Sud" (French term for the Southern Cross constellation), is the French word for "cross".
- Meanwhile, her surname, "Meridies", is the Latin word for "noon" and "south".
- Thus, "Croix Meridies" can be translated as the Southern Cross constellation. This both a reference to the similarly named antagonist group from Inferno Cop, a previous work by Trigger, and Croix's position in the final of an anti-villain.