The X-Files is an American science fiction–supernatural television series that originally aired on the Fox network from September 10, 1993 to May 19, 2002. The series 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. Mulder is a believer in the paranormal, and the skeptical Scully 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. Beginning with the eighth season, Duchovny's role was reduced from lead actor to an intermittent lead role.