The Buffyverse canon consists of materials that are thought to be genuine (or "official") and those events, characters, settings, etc., that are considered to have inarguable existence within the fictional universe established by the television series Buffy the Vampire Slayer. The Buffyverse is expanded through other additional materials such as comics, novels, pilots, promos and video games which do not necessarily take place in exactly the same fictional continuity as the Buffy episodes and Angel episodes. Doctor Who, Star Trek, Star Wars, Stargate and other prolific sci-fi and fantasy franchises have similarly gathered complex fictional continuities through hundreds of stories told in different formats.