Darth Calamity

Darth Calamity was the apprentice of Darth Lettow. When Lettow stepped down as Dark Lord for his own personal purposes, Calamity bested Netharion for the throne and became the Dark Lord of the Sith. However, when he was challenged once again by Darth Udûn and Darth Nefarius, he disappeared. There were rumors of his return to Korriban years later, though the rumors were never confirmed.