Not every Sailor Guardian from the Sailor Moon manga was present in the original anime. With the more manga-faithful Sailor Moon Crystal about to adapt the Dream arc, the Guardian forms of the Amazoness Quartet are likely to make their first anime appearance. If Crystal reaches the Stars arc, several more previously unadapted Guardians will also get a chance to be animated.
Even in Crystal, however, there are a few Sailor Guardians that will likely never make an appearance, since they originate from spinoffs or adaptations outside of the main canon. These include characters from stage musicals, live-action television, video games and even noncanonical manga stories.
Parallel Sailor Guardians
The manga short story Parallel Sailor Moon takes place in an alternate universe where Usagi Tsukino is an adult with two daughters: her canon future daughter Chibiusa and a younger girl named Kousagi. In the story, Kousagi becomes an unnamed Sailor Guardian, along with the daughters of the other four Inner Senshi. Kousagi's costume has a unique rabbit theme, and her adventure is notably more surreal than canon Sailor Moon storylines, with the Parallel Guardians having to protect Earth from an approaching meteor -- which turns out to actually be a horde of extraterrestrial rabbits.
Despite technically being part of the manga, Parallel Sailor Moon is not part of the main story. In fact, it directly contradicts canon, so it's unlikely we'll ever see Kousagi and her friends onscreen. The story is also quite short, and both the girls' Guardian forms and the story's new cat mascot go unnamed.
Sailor Luna
The early 2000s live-action series Pretty Guardian Sailor Moon made several changes to the source material. One of the biggest was giving talking cat mascot Luna a Guardian form of her own. In the manga and most adaptations, Luna's human form is portrayed as an adult, but in Pretty Guardian, Sailor Luna is a little girl with cat ears and a tail, designed to appeal to a young audience. She essentially takes on the role Chibiusa takes in the original, being a child Guardian who adopts the Tsukino family name.
Despite being a very different character than the canon Luna, Luna Tsukino and her Guardian form were actually designed by series creator Naoko Takeuchi. Another change to Luna's character in Pretty Guardian is that her mascot form is portrayed as a plush cat rather than a real cat.
Princess Sailor Moon
This version of Sailor Moon also only appeared in Pretty Guardian. Princess Sailor Moon is controlled by the personality of Usagi's past-life identity Princess Serenity, who is portrayed in the live-action series as cold and uncaring towards anyone other than Prince Endymion. Serenity took over as Princess Sailor Moon when Usagi became overwhelmed by sadness, and Usagi struggled to curb Serenity's extreme behaviors.
Princess Sailor Moon is incredibly powerful, and like the canonical Sailor Saturn, she has the capacity to destroy the world, which she is willing to do if she thinks it will reunite her with Endymion. It is unknown if Naoko Takeuchi designed Princess Sailor Moon, as she did with Sailor Luna, but she has drawn her.
Sailor Astarte
Appearing in the Sailor Myu musicals, Sheba Shingetsu Astarte (with Sheba spelled Siva in some promotional materials) is the incarnation of the Phonecian goddess Astarte, as well as a Sailor Guardian. Her Guardian form is also connected to the moon, linking her to Usagi, and she is extremely powerful. Astarte is manipulated by the villains Lilith of Darkness and Dark Cain, and although Sailor Moon does her best to save her, she is ultimately unable to.
Sailor Astarte is a somewhat odd character within the Sailor Moon universe. Unlike most Sailor Guardians, who usually are or are reincarnated from alien princesses and warriors, she is literally a mythical goddess. Her powers, as well as those of Lilith and Cain, draw from Judaism, with her attacks referencing Solomon. Despite Sailor Astarte being treated as a moon Guardian, the mythological Astarte is considered an equivalent to Venus. In the canonical Sailor Moon universe, Moon and Venus have both been main protagonists, which perhaps makes Astarte’s villainous connections more surprising.
Additional Shadow Galactica Members
There are several villainous Guardians within Shadow Galactica, the evil group led by Sailor Galaxia in the Stars arc. While a few of these characters are likely to appear in anime for the first time in Crystal, a few of them are exclusive to the musicals. These include two members of the animal-based group the Sailor Animamates, Sailor Pewter Fox and Sailor Titanium Kerokko (based on a frog and renamed Sailor Mitis Kerokko in one musical), as well as Sailor Theta and Sailor Buttress.
Sailor Theta is a minor character who works alongside Galaxia's canonical followers Sailor Phi and Sailor Chi, while Sailor Buttress is Galaxia's advisor and second-in-command, giving orders to the other members of Shadow Galactica on her behalf. Buttress is notable for not having a space-, metal- or mythology-themed name, instead being named after a structure for reinforcing walls.
The Opposito Guardians
The Opposito Guardians are a villainous group appearing in the Super Famicom game Sailor Moon: Another Story. Each was a dissatisfied citizen of 30th century Crystal Tokyo recruited by the villain Apsu to fight the Sailor Guardians and obtain the Silver Crystal. Each Opposito Guardian is a counterpart to one of the Inner Guardians, and their names are taken from Babylonian and Sumerian mythology. Sin is the counterpart to Sailor Moon, Nabu to Sailor Mercury, Nergal to Sailor Mars, Marduk to Sailor Jupiter, and Ishtar to Sailor Venus.
The Opposito team is lead not by Sin, but by her younger brother Anshar, who befriends Chibiusa and finds his loyalties torn between her and his sister. Sin and Anshar's parents were killed by the Black Moon Clan, which they blame the Sailor Guardians for, and the other members of the group have their own reasons to be unhappy with Crystal Tokyo's society. In both of the game's endings, the Opposito Guardians return to their regular lives when Apsu is defeated.
