Mythology (also referred to as a mythos [1] ) is the term often used by fans of a particular book, television, or film series to describe a fiction franchise's overarching plot and often mysterious backstory. Daniel Peretti argues that mythology "is often used emically to refer to back story". [2] The term was pioneered by the American science fiction series The X-Files , which first aired in 1993. [3] With this being said, many other forms of media have some sort of mythology, and the term is often applied in regards to Buffy the Vampire Slayer , Lost , and the Batman and Superman comics, among others. [2]
Some fictional series more literally have a mythology, i.e. a cycle of fictional myths, as part of the in-universe material. An unusually well-developed and comparatively early example is that of the legendarium of J. R. R. Tolkien (including his Middle-earth stories), for which he developed written myths and epic poems, some in fictional languages like Elvish.