Sith Empire (Great Sith War)

The Sith Empire was a government of the Sith ruled by Exar Kun in the Great Sith War. Darth Sion fought as a Sith Marauder for it. After the Empire's collapse, many of its remnants and former leaders sought to restore it to power; ultimately, it would be resurrected in the form of the new Sith Empire of Darth Revan and Darth Malak.

Behind the scenes
The relation of the Sith Empire to the Brotherhood of the Sith is not said, though both are mentioned separately in the Knights of the Old Republic Campaign Guide.

Appearances

 * Star Wars: Knights of the Old Republic