The Sith Emperor (feminine Sith Empress) is the undisputed leader of the Sith Empire. Some rule supreme in their rule by using the dark magics of the Force to enslave or brainwash their subjects, while others inspire loyalty through military dominance or pure charisma. There has been only one Sith Emperor since the Great Hyperspace War in over 1,300 years ago and that is Lord Vitiate. He brought a bold vision to the Sith Empire and made the Empire a force of dominance that challenged the Galactic Republic. Lately, Vitiate has been an absent Emperor and was supposedly vanquished by a Jedi Knight in a conflict, leaving the ruling of the Empire to the Dark Council.
With the sudden arrival of the Eternal Empire, the galaxy was turned upside down. The Eternal Fleet struck both the Sith Empire and the Republic at once, first targeting their shipyards, then cutting off supply lines. Within months, Dromund Kaas and Coruscant were blockaded. Without Darth Marr's leadership, the Dark Council scrambled to fight back against Arcann's forces and were ultimately defeated. While most council members were killed, others disappeared to unknown corners of the galaxy. When the dust settled, only Darth Acina remained, and she quickly named herself the new Sith Empress.