The X-Files premiered in 1993, created by Chris Carter, and its theme was composed by Mark Snow. The simple whistled tune became inseparable from agents Mulder and Scully and their investigations into paranormal cases. In Spanish-speaking countries the series is known as Expediente X or Los Expedientes Secretos X, which is why the clip circulates under that name. Online, the music survived long after the original run as shorthand for aliens, UFO sightings and unbelievable stories, and it is still dropped into edits whenever something seems too strange to explain.