In fiction, a canon is material accepted as being authentically produced by an author or an ascribed author. Canon is often contrasted with, or used as the basis for, works of fan fiction and other derivative works. Origin Canonicity When there are multiple "official" works or original media, what material is canonical can be unclear. This is resolved either by explicitly excluding certain media from the status of canon (as in the case of Star Trek and Star Wars), by assigning different levels of canonicity to different media (as was in the case of Star Wars before its ownership by Disney), by considering different but licensed media treatments official and equally canonical to the series timeline within their own continuities' universe, but not across them, or not resolved at all. There is also no consensus regarding who has the authority to decide what is or isn't canon, with copyright holders usually declaring themselves the authorities when they want to erase or retcon materials that were approved by the setting's original creator (with Star Wars again being an example). The use of canon is of particular importance with regard to reboots or re-imaginings of established franchises, such as the Star Trek remake (2009), because of the ways in which it influences the viewer experience. Examples The official Star Trek website describes Star Trek canon as "the events that take place within the episodes and movies" referring to the live-action television series and films, with Star Trek: The Animated Series having long existed in a nebulous gray area of canonicity. Events, characters and storylines from tie-in novels, comic books, and video games are explicitly excluded from the Star Trek canon, but the site notes that elements from these sources have been subsequently introduced into the television series, and says that "canon is not something set in stone." Some non-canonical elements that later became canonical in the Star Trek universe are Uhura's first name Nyota, introduced in the novels and made canonical in the 2009 film Star Trek, and James T. Kirk's middle name Tiberius, introduced in the Star Trek animated series and made canonical in Star Trek VI: The Undiscovered Country. During George Lucas' time with the franchise, Star Wars canon was divided into discrete tiers that incorporated the Expanded Universe (EU), with continuity tracked by Lucasfilm creative executive Leland Chee. Higher-tier and newer material abrogated lower-tier and older material in case