Esorr Kayin was a male who was the Sith apprentice of a member of the Dark Council during the Cold War. He murdered the apprentice of Lord Necus in the second-floor library of the Sith Academy on Korriban, and the deed was witnessed by another acolyte named Alif, who Kayin threatened into remaining silent. However, Alif was later interrogated and the culprit's name revealed; Inquisitor Zyn was unable to punish Kayin on account of his master's status as a Dark Council member, though Necus himself intended to exact retribution.