An unofficial UniverseCompendium.

When the makers of a series can't be bothered to put together a proper compendium, you can always rely on the fans to do it for you. With typical obsessiveness, they will go through and document everything that is known about the series, and, on occasion, bind it together into a book. [[TheWikiRule Or a wiki]].

The results differ from a UniverseCompendium in several ways:
* A concordance will tend to document more thoroughly what actually happened on-screen. The folks who write compendia tend to not have quite the same attention to detail as a really obsessed fan.
* Since the concordance author has no way of knowing what the writer thought was actually important, unimportant details often receive more notice in a concordance than in a compendium. Thus, you are more likely to discover a really obscure fact in a concordance.
* A compendium will often be distilled in such a way as to cover up [[RetCon retcons]] or embarrassing but inescapable mistakes in the show's past. A compendium is more likely to tell you what the show's makers actually ''intended'', while a concordance is more likely to tell you what they actually ''did''.
* A concordance will often contain {{fanon}} (which, since it's in a proper book by someone who knows what they're talking about, will be taken as WordOfDante). While a compendium may later be proved wrong on some point, we can be assured that what is written was actually what the writers thought was going on at the time.
* Many paper-and-pencil RolePlayingGames based on literary or mass-media properties qualify as {{Universe Concordance}}s, despite having official licenses, because the creators of the RPG often have minimal communication with the creators of the property it's based on.

From time to time, the producers of a series will come across a concordance and [[AscendedFanon begin treating it as gospel]], as it contains far more detail than any of their own internal documentation.

As these are almost always unauthorized publications, they tend to exist in the same legal gray-market as FanFic, though it should be remembered that scholarly reference works have historically been considered fair use of copyrighted material, hence the existence of academic literary journals.

Rowling vs. RDR Publications, while preventing the Harry Potter Lexicon from being set in print, established a precedent that {{Universe Concordance}}s have the right to exist over-the-counter under two conditions:
# There are not too many direct quotes from the source material, especially unattributed ones; and
# The Universe Concordance does not borrow heavily from any UniverseCompendium, with or without direct quotes.

So, they are now officially encouraged.

Online, unofficial web sites, [[TheWikiRule particularly Wikis]], have taken up the slack, with the {{Trekverse}} Wiki, [[ Memory Alpha]] as the first example.



[[folder:Anime & Manga]]
* [[ The Digimon Encyclopedia]] by Chris [=McFeely=]. Covers Adventure, Adventure 02, and Tamers (and part of Frontier). Long before Wikipedia, this was the source for anything in the Digimon anime.
* ''{{Pokemon}}'' [[ Bulbapedia]], which is also tied into an alliance of sorts with several Pokemon wikis in other languages. Bulbapedia covers all aspects of the fandom, including the anime,manga,video games ect.

[[folder:Comic Books]]
* [[ The Appendix to the Handbook of the Marvel Universe]], so well-researched that MarvelComics has hired the senior staff to help write the newest versions of the ''official'' UniverseCompendium.

* [[ Wookieepedia]], the ''StarWars'' wiki. Much more detailed than either printed Star Wars encyclopedias or the official online Star Wars Databank.
* [[ Pandorapedia]]. Everything you could ever possibly want to know about ''Film/{{Avatar}}''.
** [[ James Cameron's Avatar Wiki]] serves this purpose as well.
* ''Franchise/PlanetOfTheApes'' has several. Online, there's The Sacred Scrolls, and there are also a number of hard copy guides. Probably the most extensive are 'Lexicon of the Planet of the Apes' and 'Timeline of the Planet of The Apes', both by Rich Huntley.

* Elyse A. Dickenson's ''The Forrester Papers'' is very probably the only complete documentation to ''[[Series.WarOfTheWorlds War of the Worlds]]'' ever written.
* The ''Franchise/CthulhuMythos Encyclopedia'' by Daniel Harms.
* [[ The Yellow Site]] for the Yellow/Hastur/Carcosa Mythos, founded upon Victorian weird-fiction classic ''Literature/TheKingInYellow'' and frequently connected to the Cthulhu Mythos.
* The ''Literature/HarryPotter'' Lexicon.
* The [[ Annotated Pratchett File]]
* [[{{Dragaera}} Steven Brust]] uses fan-created concordances and timelines as references when he continues his series.
* ''Franchise/TheDarkTower Concordance'', without which Creator/StephenKing claims he wouldn't have been able to complete the series.
* ''{{Literature/Animorphs}}'' [[ Seerowpedia]]

[[folder:Live Action TV]]
* Far and away the most famous is Bjo Trimble's ''The Star Trek Concordance'', which was the prime source for information to fans until Paramount began releasing its own compendia in the 1980s. The makers of early ''Franchise/StarTrek'' feature films and ''Series/StarTrekTheNextGeneration'' consulted it heavily, as it was the best single resource in existence at the time.
** And in the Age of Internet, there is the Star Trek wiki ''[[ Memory Alpha]]''.
* A long-standing rumor from the '80s suggests that FASA lost the license for the ''Star Trek'' RPG because authors were drawing on FASA ship design and game {{Fanon}} for their licensed novels.
* Along with Wookieepedia, Series/{{Lost}}pedia is commonly cited as one of the most comprehensive wikis about a fictional universe in existence. Writers Damon Lindelof and Carlton Cuse have admitted using Lostpedia when they need to remember a quick fact while writing an episode.
* Since the early '80's ''Doctor Who Programme Guide'' (which went through three editions), the Franchise/{{Whoniverse}} has had countless licensed and un-licensed examples. Online compedia include [[ The Whoniverse]], the no-longer-available-on-the-Web Outpost Gallifrey reference guides, [[ The Doctor Who Guide]], the staggeringly detailed [[ "Rassilon, Omega, and that Other Guy"]] and the [[ TARDIS Index File Wiki]].
* ''[[Series/BabylonFive Babylon 5]]'' has [[ The Lurker's Guide]].

[[folder:Video Games]]
* [[ The Marathon Story Page]], it's...comprehensive, so to speak, as a conversation below puts it:
--> '''Anonymous:''' Can you briefly summarize the plot of the Marathon series? I found one at [[ some fan site]], [[PlayTheGameSkipTheStory but it was a fucking doctoral thesis]].
--> '''Durandal:''' That '''was''' the summary. The full story is the equivalent of [[NumerologicalMotif 7]] of your doctoral theses.
---> [[ The Conversatron]]

[[folder:Web Animation]]
* [[]], ''the'' ''WebAnimation/HomestarRunner'' reference site, which the Brothers Chaps have commented on going to when they can't remember their earlier work.

* ''Webcomic/ElGoonishShive'' possesses an unofficial wiki, called [[ Shiveapedia.]] [[WordOfGod The author himself]] declared its timeline of story events canon.

[[folder:Western Animation]]
* Due to the literally hundreds of episodes, stories, characters and locations, the TTTE Wikia has become a handy reference point for writers on ThomasAndFriends.

* {{Wikipedia}} can be thought of as a Universe Concordance for RealLife.
** And fiction as well, though that was not what its founders intended (at least not to such a degree.)
** Pages that "fail to make a clear distinction between fiction and real life" (read: using the page as a Universe Concordance) are flagged and sometimes deleted. Then of course there's the "inclusionist vs. exclusionist" debate which is basically about editors fighting over whether Wikipedia should be used as a Universal Concordance or not.