A humanoid, during the era of the Jedi Civil War, was a Sith Knight who gave service to the Sith Empire. This Knight was under the direct leadership of Darth Revan, the Dark Lord of the Sith who headed the Sith Empire, and this Knight additionally trained the Sith apprentice known as Darth Voren, during that time.
In August of 2008, Patrick Stutzman authored The Betrayal of Darth Revan, a role-playing supplement, which contained a mention of the Sith Knight.