Darth Kalen

Darth Kalen was a sith lord during the rebelion era. He felt the Darth Sidious was unsutable to rule the sith, having not reavealed to the general public that he was a sith. He planed to overthrow Sidious with a mersilous sith empire. Using mainly clone wars leftovers for his army he was not considerd a real threat to the Empire.