The Outer Senshi

Outer Senshi is a fan canon term typically referring to Sailor Uranus, Sailor Neptune, Sailor Pluto, and Sailor Saturn from the anime/manga series, Bishoujo Senshi Sailor Moon.

The Outer Senshi, those who defend the solar system from external threats, take their names from the four planets furthest from the sun (as reckoned at the time the series was created): Saturn, Uranus, Neptune, and Pluto. The series treats these characters very differently than do the fans—they are considered a group of three, with Saturn excluded due to her unique role in the story, however, Saturn does join them later in the series after the third arc. In the manga, they are officially called the "outer solar system warriors" (or gaibu taiyokei senshi), and use this name to refer to themselves in the anime as well. The Guardian Senshi usually refer to them as "Uranus-tachi," meaning roughly "Uranus and the others." In the age of the Silver Millennium, Sailors Uranus, Neptune, and Pluto guarded the edge of the solar system and had instructions to fend off any alien attacks. Sailor Saturn was not among them, as she is the bringer of destruction and ruin. In the manga, their backstory becomes more complicated: it had always been the other Outer Senshi's duty to prevent Sailor Saturn's summoning, but when they gathered to witness the Moon Kingdom's destruction at the hands of the Dark Kingdom, the Outers inadvertently allowed Saturn to be summoned so that she could destroy the remnants of the kingdoms of Earth and Moon. All four are then reborn as in the anime. In both storylines, Sailor Pluto plays a double role as the guardian of the Gates of Time (the manga extends her duties by hinting that she is also guardian of the underworld).

On Earth, Sailor Uranus and Sailor Neptune become, respectively, Haruka Tenoh and Michiru Kaioh, partners and implied lovers a year older than the Guardian Senshi. They work together for some time, only later joined by Setsuna Meioh (Sailor Pluto), a college student, and by Hotaru Tomoe (Sailor Saturn), a much younger girl (whose age varies due to rebirth and accelerated growth).

The Outer Senshi appear charming, mature, and personable in their civilian forms, and the Guardian Senshi admire them enormously. However, they also demonstrate extreme dedication to their role as soldiers, and, should they determine that sacrifices need to be made, can be entirely ruthless with allies as well as enemies. While in Senshi form, Uranus and Neptune are cold, aloof, and are not inclined to trust offers of help from other groups, preferring to work alone, even to the exclusion of the Guardian Senshi, while Pluto and Saturn often help the Guardian Senshi. Pluto mediates between Uranus and Neptune and the other Senshi. The manga shows that, even if the Outer Senshi prefer to exclude the Guardian Senshi, they love Princess Serenity very tenderly - to the extent that they would treat her with complete disrespect to protect her. They regard Prince Endymion with utmost courtesy and even go out of their way to care for Chibiusa.

Each of the Outer Senshi fights with a special weapon; Uranus, Neptune, and Pluto bear the three Talismans, and Sailor Saturn carries the Silence Glaive, which is capable of destroying whole worlds. In general, the Outer Senshi are more powerful and more experienced than five out of six Guardian scouts: Sailor Uranus is physically the strongest by use of her Space Sword, Sailor Neptune is granted special visions by use of her Deep Aqua Mirror, Sailor Pluto can stop time itself by use of her Garnet Rod, and Sailor Saturn is regarded as the most powerful of all, second only to Sailor Moon (she is even able to block attacks from Sailor Galaxia, one of the most powerful Senshi in the universe).