The X-Files is an American science fiction–supernatural television series that originally aired on the Fox network for nine seasons from September 10, 1993, to May 19, 2002. The series centers on FBI special agents Fox Mulder and Dana Scully, who work on cases linked to the paranormal, called X-Files. Mulder, an FBI profiler, is a believer in the paranormal, and the skeptical Scully, a medical doctor, is assigned to make scientific analyses of Mulder's discoveries which could ultimately be used to discredit his work. Throughout the series the two develop a close friendship. During the eighth and ninth seasons of the series, Duchovny's role was reduced from lead actor to an intermittent lead role.