X (on the window) - On the fantasy drama THE X-FILES/FOX/1993-2002 conspiracy obsessed FBI paranormal investigator Fox "Spooky" Mulder (David Duchovny) would place the letter X made from masking tape on the window pane of his apartment and shine a light through it to summon his mysterious source named Mr. X. (Steven Williams). The "X" gimmick first surfaced on episode No. 31 "One Breath."  During the first season, Mulder had communicated with a mysterious government agent called "Deep Throat" (Jerry Hardin) via a blue light shining from his apartment window. On episode "E.B.E.," Deep throat called Mulder and signaled him with a series of clicks. See also - NICKNAMES - "Deep Throat" and SIGNOFFS - "SRSG"