Darth Immorus

"We will plan an attack on the New Jedi Order, and make them all parish. After that, slaughter all the Senators on Corusaunt. Do you understand me?"

- Darth Immorus to the Sith Council

Darth Immorus is a Sith Lord who lead the Sith Order in the Great Civil War. He had 3 apprentices, Darth Revasan, Darth Hadeis, and Darth Demetruse. He killed Darth Demetruse because he thought his power was not as strong as it should be.

About
He has lived for over 1,000 years, born at the end of the Old Republic era. He was the one who commanded the 20 membered Sith Council. And at the end of the Great Civil War, he fled into an unknown planet in a Sith Shuttle, with two commandos, one commander, and two pilots. He most likely killed them when they got to their destination.