Revan

Revan, who was called the Revanchist, Revan the Butcher, and the Prodigal Knight, was born around 3,994 BBY, presumably in the Outer Rim, and studied under several Masters of the Order. In the Mandalorian Wars he led volunteers into battle in defiance of the Council's prohibition, and Malak joined him.

After defeating the Mandalorians, Revan and Malak set out to find the source of their strength and came to the throne room of the Sith Emperor, who bent their minds and completed the fall of both to the dark side. Having become a Dark Lord, Revan used the star maps to find the Star Forge in the Lehon system and unleashed the Jedi Civil War against the Republic and the Order.

Captured by the Jedi, he lost his memory and was retrained as a Jedi, after which he destroyed the Sith empire he himself had created, along with the Star Forge. Later he obtained the mask of Mandalore and departed into the Unknown Regions, where he was captured by the Sith Empire and spent centuries in captivity; his name remained the stuff of legend for both the Jedi and the Sith.