Star Wars: 10 Most Powerful Sith Lords

The Sith weren't originally a order, but an actual species that Dark Force users only later coalesced around. Naga Sadow was the last of the species, taking up leadership of the Sith Empire 5000 years before the Battle of Yavin and forming a lot of the key facets of the order.

Like many of the early Sith, the story of his time in power is excessively complex and rather exhausting to relay, but in short it was dominated by conflict with another inheritor of the Dark Lord flame whom he eventually overpowered at the cost of the Sith's strength due to the ongoing Great Hyperspace War, so he lived in exile for centuries, honing the Sith craft and building Yavin IV's temples. His main adding to the Sith tradition came about by accident, however: he eventually took on an apprentice, former Jedi Freedon Nadd, who learnt everything he knew before killing Sadow.

That oversight aside, however, the practical skills and definition of the Sith order Naga Sadow showed vastly eclipse all but a few who followed him. Like many from this time he lived on as a possessing ghost, but he was less involved as some.