Sith Lord

Sith Lord, also known as a Lord of the Sith, was a title conferred upon members of the Sith Order. Sith Lords drew upon the dark side of the Force, using it to gain power.

The title "Darth" was given to newly christened Sith Lords in place of their old identities. It roughly translated to "Dark Lord." Following the defeat of the Sith, Darth Bane limited the Order's ranks to two Sith Lords—a Sith Master and a Sith apprentice—at any one time under the Rule of Two. The establishment of the Galactic Empire a millennium later saw the galaxy controlled by the Sith Lords Darth Sidious and Darth Vader.

Text and facts from the “Sith Lord” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.