Darth Shaar was a Sith female who was a Sith Lord of the Sith Empire during the Galactic War.
Shaar on Belsavis
A particularly passionate Sith, Shaar had a "vigorous" relationship with Lord Raxxus in her youth several decades before the Galactic War, though their relationship soured and the radical Sith was marked for death by the Dark Council before Raxxus was captured by the Jedi. During the invasion of Belsavis, Shaar learned that Raxxus was among the prisoners on Belsavis, and enlisted Imperial aid in eliminating her former lover.
Lord Shaar would continue her service to the Empire for several years, even surviving the Eternal Empire's invasion to the known galaxy. In that time, she became a Darth and operated freely within the Empire's civil administration.
Lord Shaar was a crafty and hedonistic individual who excelled at the game of Sith politics, knowing how not to appear threatening and maintaining many contradictory alliances until ready to strike. She liked to savor physical and experiential luxuries provided by her position in the civil administration.
Lord Shaar appears on Belsavis in the video game Star Wars: The Old Republic, where she provides Imperial players with the Heroic mission "Old Enemies." Darth Shaar is voiced by Lucy Robinson.
For players that sided with the Republic on Iokath and killed Empress Darth Acina, Shaar is stated to have ascended to the Dark Council as an overseer of the Sphere of Civil Administration, replacing Darth Vowrawn who would have become Emperor under these circumstances. Alternatively, if Jace Malcom is killed in Acina's place, then Shaar remains a Lord of the Sith.
If the player supports the Republic in the Onslaught expansion, they will meet Shaar at the Huttbreaker's auction. In the aftermath of the Empire's attack on the Mek-Sha docks, Tau Idair notes that Shaar was missing and speculated that she either fled or was amongst the Imperial shuttles the Republic shot down.
Lana Beniko kills Darth Shaar and Darth Vowrawn.
If the player supports the Empire in the Onslaught expansion, Shaar will be the player's liaison throughout their operations on Mek-Sha. If Acina is the Empress, Shaar will be accompanied by Darth Vowrawn. If Vowrawn is Emperor, then Shaar alone will direct the Commander. If the player is a Saboteur for the opposing faction and sabotaged Shaar's plan to destroy the Republic fleet, the player can order Lana to kill Shaar (and Vowrawn if he's present) by decapitation.
Imperial players have the option to flirt with her regardless of gender, which she will seemingly reciprocate. If the player flirts with Major Anri after she changes her outfit, Shaar will agree with the player's sentiment, indicating an interest in the Major as well.