A Sith Lord During The Jedi vs. Sith war.  He knew that the current order would not last and the sith would eventually kill each other in the mad struggle for power, as they did.  He alone survived and started the "New Sith" which were influenced bythe rule of two, making it impossible for more then two Sith to exist at once, those two would be a master and his apprentice.  He studied under Lord Qordis, had a violet lightsaber and started the  tradition of all Sith to be named "Darth".