A friend of Deep Throat, who to further Mulder´s investigations was giving him secret information. Unlike Deep Throat, this information seemed to be given relucantanly. He would not risk his own neck for Mulder and he had more than once admitted that he was afraid of getting killed like his predecessor. It was reavealed that X worked for
the Cigarett Smoking Man, but may have had his own agenda, and following this mysterious agenda in "Talitha", he took surveillance photos of a meeting between the Cigarett Smoking Man and Mulder´s mother. However, unknown to X, the Cigarett Smoking Man found out about these pictures, and for what he had known was a leak in their organization, he laid a trap. His trap was sprung in "Herrenvolk" and X was tricked into revealing his betrayl. This left him shot to death on Mulder´s doorstep, and with the last moments of his life, he leaft a message for Mulder, S R S G , four initials that led Mulder to a new player in the game, a woman called Marita Covarrubias. With his death, X may have left more questions than answers.