File:Ajunta Pall.jpgAjunta Pall, the first Dark Lord of the Sith
Dark Lord of the Sith is the formal title taken by the Grand Master as the Sith Master of the Order of Sith Lords.
While holding the title of Dark Lord of the Sith the Grand Master may style himself as either Lord or Darth. Upon retirement, a Grand Master loses their position as Dark Lord and become an ordinary Sith Lord.
The current Dark Lord of the Sith is Muz Ashen.
History
File:Revan and Malak.jpgDarth Revan and Darth Malak, both Dark Lords of the Sith at different times.
Kane Vader, the Brotherhood's first reigning Dark Lord of the Sith.
The title of Dark Lord of the Sith (Dark Lady of the Sith, if referring to a woman) originally referred to the emperor of the Sith Empire, and later was taken by the leader of the Sith Order. Before Lord Kaan, there was only one Dark Lord of the Sith at a time, who was the head of the Order - in more recent periods, it was a title shared by multiple individuals simultaneously.
The title Dark Lord of the Sith is often thought to be synonymous with the title Darth, but this is purely conjecture and has not been properly substantiated. Many Sith Lords have used the Darth title, but there is no evidence as to the synonymity of these two appellations.
The title of Dark Lord was possibly comparable to that of a Jedi Grand Master.
File:Vader and Palpy.JPGDarth Sidious and Darth Vader, Dark Lords of the Sith according to Bane's Rule of Two
History of the title
The first Dark Lord of the Sith was the leader of the exiled Dark Jedi who, after their defeat in the Hundred Year Darkness conquered the Sith species and ruled over them as gods.
Darth Ashen, current Dark Lord of the Sith.
Xendor, believed to be the first Dark Jedi, is possibly the predecessor of the Dark Lords of the Sith, though he himself was never a Sith Lord.
After the fall of the Sith Empire, Naga Sadow gave the title to his apprentice, Freedon Nadd. The spirit of the dead Dark Lord Marka Ragnos then declared Nadd’s apprentice, Exar Kun, Dark Lord of the Sith. 3,000 years later, Lord Kaan began the practice of giving the title to all members of the Order, thus making it a title shared by many Sith for the first time in their long history. After the institution of the Rule of Two, the title was naturally held by only two members at a time, one being the Sith Master and the other being the Sith Apprentice.