Fancruft is a term sometimes used on Wikipedia to imply that a selection of content is important only to a small population of enthusiastic fans of the subject in question. The term is a neologism derived from the older hacker term cruft, describing obsolete code that accumulates in a program.

While "fancruft" is often a succinct and frank description of such accumulations, it also implies that the content is unimportant and that the contributor's judgment of the topic's importance is clouded by them being a fan. Thus, use of this term may be regarded as pejorative, and when used in discussion about another editor's contributions, it can sometimes be regarded as uncivil.

As with most of the issues of What Wikipedia is not in Wikipedia, there is no firm policy on the inclusion of obscure branches of popular culture subjects. It is true that things labeled fancruft are often deleted from Wikipedia. This is primarily because articles labeled as fancruft are often poorly written, unwikified, non-neutral, unreferenced, or contain original research. These issues may contribute to deletion. Such articles may also fall into some of the classes of entries judged to be "indiscriminate collections of information". Well-referenced and well-written articles on obscure topics are from time to time deleted as well, but such deletions are controversial. It is also worth noting that many articles on relatively obscure topics are featured articles.

Generally speaking, the perception that an article is fancruft can be a contributing factor in its nomination and deletion, but it is not the actual reason for deletion. Rather, the term fancruft is a shorthand for content which one or more editors consider unencyclopedic, possibly to the extent of violating policies on verifiability, neutrality, or original research.

The use of the term implies that an editor does not regard the material in question as encyclopedic, either because the entire topic is unknown outside fan circles, or because too much detail is present that will bore, distract or confuse a non-fan, when its exclusion would not significantly harm the factual coverage as a whole.

Some users consider this a pejorative term and see it as insulting to well-meaning contributors. They might likewise consider use of the term in forums such as articles for deletion inappropriate, but it is, nevertheless, in common use there. However, this usage is not a substitute for a well-reasoned argument based on existing Wikipedia policies.

The question of what material is encyclopedic is likely to remain hotly debated. That said, the issue becomes more muddled when the topic concerns a piece of fiction. The term "fancruft" is most commonly applied to fictional works and pop culture.

It is, of course, possible to write in great detail on fiction in a way that is factually accurate, espouses the neutral point of view and is not original research, but historically, encyclopedias do this only in the context of representing critical points of view (e.g. when engaged in literary criticism).

Some works of fiction are particularly likely to inspire articles that may be criticized as fancruft, particularly works with a great number of characters, places, events, and important objects, such as the Star Wars universe, which spans several feature films as well as hundreds of novels and other media; the Star Trek universe, which spans several TV series comprising multitudes of episodes, films, and countless novels; and the Pokémon universe, a popular media franchise which has more than 1200 characters, including more than 1,000 species. Fan fiction, in whatever fictional realm, is rarely considered encyclopedic.

Debates often arise between contributors who point out that the topic on which they are writing is popular (and thus important) and those who believe that, regardless of a fictional universe's popularity, having well over 500 articles devoted to specific episodes of The Simpsons, an American animated television series and a single article on Paradise Lost makes Wikipedia appear biased towards pop culture and against "serious" subjects such as the Western canon. Of course, as Wikipedia is a wiki, its materials can be said to reflect readers' priorities, since anyone may add more information about their preferred subjects and become an editor. However, the issue of systemic bias is a real one, as is the issue of bias in the form of deletion of verifiable material on the vague grounds of it being "unencyclopedic."

One of the major aspects of fancruft articles is that they tend to focus entirely on their subject's fictional relevance, as opposed to their place in the real world. Articles on episodes of television series, or fictional characters in movies are more likely to be labeled fancruft if they are primarily summaries, biographies of fictional people, or collections of trivia that relate to the continuity of a series rather than its critical or social reception. In fact, an article should not be entirely composed of summaries or biographies of fictional characters. Articles can often avoid being labeled fancruft if they avoid focusing on their subjects as fiction. See Wikipedia:Manual of Style/Writing about fiction for more about how to achieve this.

There is also a positive side to the act of describing an article as containing cruft; those who would keep the information in it are stimulated to produce a better article to avoid deletion, or merge several unviably small articles into one with clearer focus. Concentrating, say, minor characters in a series can be good for them, as giving them what some may consider the "appropriate" amount of attention may avoid their complete removal from the encyclopedia.

If the user comes across fancruft, an approach is to assume that the article or topic can be improved. If there is an insufficient amount of reliable source coverage on the topic, the focus of the discussion should be WP:Notability. More likely, the article will lack a hook—one or more interesting facts to attract or pique the interest of readers outside of the small population of enthusiastic fans of the topic. Here, the general focus of the discussion should be What Wikipedia is not (importance conveyed by sources) rather than WP:Notability (coverage by sources).

In the context of WP:NOT, the specific focus of the discussion may be that the article is a compilation of facts that reliable sources outside of fan-based reliable sources have not found interesting enough to publish. The WP:NOT question then may be whether the problem is merely a failure to include available, interesting facts (e.g., style of writing) or whether the article should be deleted under What Wikipedia is not.

Instead of immediately listing a potential WP:NOT article for deletion, it may be better to prompt those interested in the article to improve the article. There are many style of writing templates available, one of which probably will best fit the situation. {{Advert}}, {{essay-entry}}, {{fansite}}, {{gameguide}}, {{howto}}, {{likeresume}}, {{newsrelease}}, {{fanpov}}, and {{quotefarm}} are just some of the templates available at style of writing templates. Post an appropriate template on the article page and set up a discussion on the talk page. If the article is not moved out of fancruft status in five days, then consider listing the article for deletion.