In "Existence", the last X-Files episode of season eight, Alex Krycek (Nicholas Lea) is shot between the eyes and killed by FBI Assistant Director Walter Skinner (Mitch Pileggi). Krycek had been a thorn in Mulder and Scully's side since his first appearance in the series in season two when he was temporarily assigned by the FBI to work with Mulder. Of course, as it turned out, he was actually working with the Cigarette Smoking Man. Krycek played a key role in several tragedies that affected Mulder and Scully including the murders of Mulder's father and Scully's sister.