It's fairly clear that Wikipedia is considered general reference (for both SciFi.SE and many other sites).
Is wikia.com network considered general reference as well? For example for Harry Potter questions, http://harrypotter.wikia.com
There are several elements in what makes a source a general reference:
Wikipedia is a general reference in part because just about everyone has heard of it, it's usually of reasonable quality, and information rarely disappears from it. It is natural, when you want to know something, to look it up on Wikipedia, like you might look it up in a paper encyclopedia. Hence, there is no point in duplicating information that is easily found there.
Wikia, as an institution, does not meet these criteria. The wikis in there vary enormously in terms of quality, reliability and comprehensiveness. Sometimes wikis come and go (for example, there have been communities that left Wikia because they disagreed with policy changes, leaving behind content that was decent but is no longer being maintained and is slowly rotting away). Wikia, in itself, is not a general reference site.
Specific wikis on Wikia sometimes have the necessary reliability to be a general reference site. But can you make a comprehensive list? Can most people browsing the web? No. And that content may not be very durable (see above). So individual Wikia sites cannot be considered general references either.
An added factor that distinguishes Wikipedia from Wikia and other fan sites is that Wikipedia has a policy of forbidding in-universe writing. Many fan sites provide an in-universe perspective that is not comprehensible to readers who are not familiar with the material already.
For added reading, I refer your to Robert Cartaino's answer in an earlier, broader discussion on this topic.
I am strongly opposed to broadening the definition of the general reference close reason to cover sources that are not general references.
On a related note, Google should not be used as a measure to determine whether a question is a legitimate Stack Exchange question. “General reference” does not take Google into account (or at least it should not, by its definition, even if it's sometimes abused). General reference means “look it up in a dictionary / in an encyclopedia / in the manual”. It does not mean “google it”.