TV shows you definitely shouldn't watch alone at night

The X-Files (1993 - 2002)
 For a show that aired on prime time television, Fox's breakout spookfest, The X-Files, was way ahead of the curve. Creator Chris Carter got away with all kinds of boundary-pushing stuff throughout his years on the show, and while not every episode is freaky, some of Fox Mulder and Dana Scully's best investigations made us want to sleep with the lights on.