26. ‘The X-Files’
The truth is out there with this creepy opening theme, composed by Mark Snow for the television series 'The X-Files.' The show followed special FBI agents Fox Mulder and Dana Scully as they investigated paranormal and alien occurrences hidden by the government. Mulder was the believer and Scully the skeptic in this show that aired from 1993 to 2002 and spurred two films.