Sulan is the main antagonist of the Star Trek: Voyager episode "Faces".
He was portrayed by Brian Markinson, who also played Adam Hunt in Arrow and Bartel in The Chilling Adventures of Sabrina.
Sulan was a Vidiian scientist, who referred to himself as their chief surgeon. He became aware of the existence of Voyager and suspected that Klingons might be resistant to the phage, the disease that had affected his people for centuries. He therefore lured three Voyager crewmembers, Lieutenants Paris, Torres and Durst, to a planetoid and took them prisoner. He then placed Torres in a genitron which separated Torres' human and Klingon DNA and rematerialised both a human and Klingon version of her.
While the human Torres was put to work with Paris, Durst and other slaves, Sulan experimented on the Klingon Torres by deliberately infecting her with the phage. As he had anticipated, she proved resistant and fought off the disease. Sulan began dreaming of combining her DNA with his own people to cure them and also spoke admiringly of her. Playing on this, Torres spoke of Klingons' voracious sexual appetite and offered to demonstrate to him. This resulted in Sulan having Durst killed and grafting his face onto him, attempting to make himself appear more attractive to Torres. Instead, it made her furious enough to break through her bonds, overpower him and escape.
The two Torreses met up and joined forces to try and lower the forcefield around the planetoid so Voyager could beam them aboard. Sulan confronted them, threatening the human Torres to try and force the Klingon to co-operate, but was held at gunpoint by Chakotay and Paris when they joined them. As the human Torres prepared to lower the forcefield, Sulan produced a concealed weapon and fired at her, but the Klingon Torres took the shot and was fatally injured. Moments later, with the forcefield down, Voyager beamed its crewmembers aboard, leaving Sulan alone, his hopes of finding a cure shattered.