|Associates:||Sailor Phi, Sailor Chi, Sailor Galaxia|
|First Appearance:||Sailor Moon Sailor Stars|
|Actors:||Ado Endou, Azusa Katagiri|
Sailor Theta was a Sera Myu-only character, and was an additional member of Shadow Galactica. She appeared in several Sera Myu productions: Sailor Moon Sailor Stars and its revision, and Eien Densetsu and its revision, played by Ado Endou; and Shin Densetsu Kourin, played by Azusa Katagiri.
Sailor Theta, along with Sailor Phi and Sailor Chi, was one of Galaxia's foot troops: indistinguishable, rarely given dialogue, and subservient to the higher-ranking members of Shadow Galactica. Sailor Theta's outfit had yellow highlights, and she had red hair.
In Sailor Moon Sailor Stars, Sailor Theta used the alias of Shadow Bug while working under MC Fly. However, in its revision, she was simply called Sailor Theta, who (along with Phi and Chi) disguised herself as a backup dancer for the Three Lights while on Earth.
In Eien Densetsu and its revision, Sailor Theta disguised herself as a Juuban Municipal High School student. In the revision, she had shared attacks with Sailor Phi and Sailor Chi, Galactica Puppet and Galactica Cry. After being beaten by Queen Beryl in combat, Sailor Theta was destroyed by Galaxia for her failure.
- Theta is the eighth letter of the Greek alphabet.