"Memento Mori" is the fourteenth episode of the fourth season of the American science fiction television series The X-Files. It premiered on the Fox network on . It was directed by Rob Bowman, and written by series creator Chris Carter, Vince Gilligan, John Shiban and Frank Spotnitz. "Memento Mori" featured guest appearances by Sheila Larken, David Lovgren and Morris Panych. The episode helped to explore the overarching mythology, or fictional history of The X-Files. "Memento Mori" earned a Nielsen household rating of 15.5, being watched by 19.1 million people in its initial broadcast. The title translates from Latin as "remember that you will die." The show centers on FBI special agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) who work on cases linked to the paranormal, called X-Files. When Scully is diagnosed with an inoperable nasopharyngeal tumor, Mulder attempts to discover what happened to her during her abduction experience, believing the two events to be related. "Memento Mori" was written in only two days, when previous series writer Darin Morgan did not contribute a script for the season. Discussion between the writing staff led to the "obligatory" decision to have Scully diagnosed with cancer, although the decision was not unanimous. Guest actor Lovgren portrayed multiple clones of his character using post-production techniques to merge several shots, while actor Pat Skipper had a scene cut from the final episode for time restraints, later appearing in the season finale. Plot Dana Scully (Gillian Anderson) learns that she has a cancerous tumor between her sinus and cerebrum. She initially tells only Fox Mulder (David Duchovny) and Walter Skinner (Mitch Pileggi) of the diagnosis, and is determined to continue to work. The agents head to Allentown, Pennsylvania, to see Betsy Hagopian, a Mutual UFO Network member who was previously discovered to be suffering from similar symptoms. The agents learn that Betsy has died, yet find someone using her phone line. They trace the call to Kurt Crawford (David Lovgren), a fellow MUFON member. Crawford tells them that all but one of the MUFON members Scully previously met have died of cancer. Scully is skeptical of Mulder and Crawford's claims that a government conspiracy and her abduction are behind her illness. Scully visits the last surviving MUFON member, Penny Northern, who is being treated for cancer at a medical centre. Meanwhile, Mulder discovers that all the abductees were childless but had been treated