Sith Lord

"Get help. You're no match for him. He's a Sith Lord."

- Sheev Palpatine, to Obi-Wan Kenobi and Anakin Skywalker

Sith Lord was a title conferred upon individuals who followed the Sith tradition. 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".

History
During the days of the Old Republic, many individuals held the mantle of Sith Lord and fought countless wars against the Jedi Order. Eventually, however, their numbers dwindled due to infighting. After Darth Bane established the Rule of Two, Sith tradition dictated that there could only be two Sith Lords&mdash;a master and an apprentice&mdash;at any given time.

In the years leading up to the Invasion of Naboo, the Sith Lord Darth Plagueis was killed by his apprentice Darth Sidious, who at the time was also training his own apprentice Darth Maul. Sidious planted the seeds for what would become the Confederacy of Independent Systems by forming an alliance with the Trade Federation, a corporation led by Viceroy Nute Gunray and Settlement Officer Rune Haako. Sidious convinced the Trade Federation to use their army of battle droids to blockade and invade the peaceful planet of Naboo. The invasion failed and Maul was seemingly killed by Obi-Wan Kenobi, but Sidious was elected as Supreme Chancellor of the Galactic Republic.

The Sith then resurfaced ten years later. Darth Tyranus, Sidious' apprentice, met with Viceroy Gunray, and other influential magnates, on Geonosis. They formed the Confederacy of Independent Systems and started the Clone Wars against the Republic. A number of other Sith were also active during the war, such as Sidious' former apprentice Maul, Tyranus' first apprentice Asajj Ventress, and Tyranus' second apprentice and Maul's brother Savage Opress. Due to Sidious being both Chancellor of the Republic and Tyranus' master, he was able to manipulate both sides of the war, leading to Order 66, the defeat of the Confederacy, and the establishment of the Galactic Empire.

Anakin Skywalker was turned to the dark side and became the Sith Lord Darth Vader while Sidious ruled the galaxy as Emperor. Grand Moff Tarkin and Vader oversaw the construction of the Death Star battle station. However the Rebel Alliance destroyed it along with Tarkin during the Battle of Yavin. The Rebels then continue to defy Imperial rule for a further five years, culminating in the Battle of Endor with the destruction of the second Death Star and the end of the thousand-year lineage stretching from Darth Bane to the last Sith Lord, Darth Vader, when Vader died destroying his master, Darth Sidious.

Non-canon appearances

 * William Shakespeare's The Phantom of Menace: Star Wars Part the First
 * Star Wars Epic Yarns: A New Hope
 * Star Wars Epic Yarns: The Empire Strikes Back
 * Star Wars: Galaxy of Heroes