Additional information:Granted upon completion of the questline Terror in the Flesh.
We would like to thank anon for additional information.
Original Game Codex TextThe Dread Masters are powerful Sith Lords who have served the Sith Emperor for centuries as prophets, generals and advisors. Their name was earned when they studied the power of the Phobis devices, artifacts that have driven even the most depraved Sith mad with terror. This power allowed the Dread Masters to destroy entire Republic fleets during the Great War, until they were captured and imprisoned on Belsavis.The Dread Masters were known to spend years in secluded meditation on Dromund Kaas, emerging only to bring their wisdom to the Emperor or accept gifts from supplicants. Over the decades, they have become inseparable, their immense strength in the Force coming only from all six masters working in unison. Should the Empire ever succeed in freeing them from Belsavis, the galaxy will tremble before them again.
The Dread Masters