Darth Revan

Revan was a human male, Jedi Knight (twice) and Dark Lord of the Sith during the Jedi Civil War and the Mandalorian Wars. He features strongly in the game Knights of the Old Republic and is heavily mentioned in Knights of the Old Republic II. Before his conversion to the Dark Side of the force, Revan was a charasmatic Jedi Knight who led a band of followers again the destructive forces of the Mandalorians. As a commander Revan was second-to-none, defeating his enemies with tactical brilliance at each turn. Eventually however, Revan was seduced to the Dark Side along with is friend and apprentice Malak. Returning to known space, Darth Revan and Malak conducted a war against the Jedi order and the Galaxy, capturing many worlds before Revan was defeated in an ambush and presumed by many to have died.