Calumnus

Lord Calumnus was once a Jedi knight named Azerin Jibani. When the Empire fell, she was one of the more respected teachers at Korriban, with a reputation as a teacher who was both brutal, and highly effective. She produced several highly reliable Sith marauders and bodyguards during her time as a teacher. When the final command to follow a Rule-of-Two went out, she openly flaunted the mandate and left the system with over a dozen of her best students. A few weeks after the war ended, she resurfaced, leading a brazen assault on a Dreadnought-class heavy cruiser. The entire ship's crew was slaughtered, and the newly christened Corrupted Heart became the flagship of her new pirate fleet.
Calumnus has declared that the war is not over, and that she will continue to fight until every Republic ship is destroyed, and every last Jedi has died begging for mercy. Broadcasts of her manifestos, along with calls to all imperials to prepare for the 'Empire Ascendant' are regularly appearing on planetary holonets all over the old imperial territory and across the periphery systems.