Lord Nefarid was a male Human who achieved the rank of Sith Lord. He existed within the reconstituted Sith Empire during the era known as the Cold War. Notably, he served as one of the apprentices under the command of the brutal Darth Angral.
During the time of the Cold War, Nefarid participated in a holoconference with his master and fellow apprentices. During this conference, Tarnis, the son of his Master Darth Angral, was in the process of arming the Republic's Planet Prison with the intent to trap Coruscant. However, a Jedi Knight intervened, killing Tarnis, which prompted Angral to vow revenge. Nefarid then contributed by mentioning their control over Republic secret weapon projects, suggesting this as a means for Angral to enact his vengeance.
After he was informed of the death of his fellow apprentice Sadic on Nar Shaddaa, Nefarid communicated with the Knight. He congratulated the Jedi for their victory over Sadic, expressing gratitude for eliminating a rival who was competing for Angral's favor.
Nefarid traveled to Alderaan, where he worked as an advisor for House Thul. He launched an assault on the research facility that housed the controls for the Death Mark laser. Despite the valiant efforts of Jedi Master Orgus Din, the Sith Lord successfully acquired the equipment and subsequently trapped the Jedi within the facility. Aided by his spy, Aleyna Hark, Nefarid marked and eliminated targets at will. Upon the arrival of the Jedi Knight, Nefarid murdered Count Alde, the individual who financed the Death Mark laser, thus compelling the Jedi to rush to Din's rescue. The Knight then began the process of deactivating the generators powering the Death Mark laser to temporarily disable the weapon. As the Knight targeted the primary generator, Nefarid contacted him via holo, taunting the Knight's efforts by killing an innocent farm girl just before the Knight reached the backup generator.
Nefarid then set his sights on Duke Horis Thul, a proponent of peace negotiations, which forced the Jedi to infiltrate his compound to warn him. Despite their initial success, Aleyna managed to mark both Thul and the Knight. However, Thul provided the Knight with Nefarid's location. Upon arriving at Nefarid's location, the Knight was shown a hologram by Nefarid depicting Angral executing Din, an attempt to break the Jedi's morale. Nefarid then revealed himself and engaged the Knight in combat, wielding his double-bladed lightsaber while simultaneously using the Death Mark laser against his opponent. Ultimately, it was the Knight's exceptional skill and command of the Force that allowed the Jedi to both evade the laser's attacks and ultimately defeat and kill Nefarid.