Is it acceptable to reference characters someone else created in your own writing?

To the best of my knowledge, it’s okay. I see something of the sort done all the time. Just don’t use any excerpts or images or borrow anything without being very sure of your ground with respect to permissions.

I’m not a legal advisor, though. Here’s someone who supplies legal information (not advice), but I didn’t find your specific question among those he treats.

However, I just read a novel in which there were three or four references to a well-known cartoon mouse, unnamed, and I couldn’t tell whether the author (who was free with other cultural references) was being coy or just really didn’t want to tangle with the sharp-fanged Disney legal machine.

I read, see and hear references to Jane Austen, The Wonderful Wizard of Oz, Alice in Wonderland and other classics all the time. As far as I know this is acceptable.

Here is an entire discussion on the issue, which is complicated.

Basically, fully drawn literary characters are copyrightable. Their names are not.

Literary allusion, however, has always been part of the writer’s stock in trade.

IDK.. I write fanfics all the time, so I really have no idea if it’s OK or not… I think it’s called allusion, when you reference someone famous from pop culture, mythology or somethin’...

You can say your character is a fan of Harry Potter.

You can’t say your character is a friend of Harry Potter.

For one of your own characters to speak about another character is allowed. To actually use someone else’s character or setting is questionable, depending on the copyright laws of your country (copyright laws in the US are a bit stricter than most other countries’ [and then there’s the Berne Convention which covers international copyright issues]).

Some writers don’t care, even encourage it (going so far as to publish a canon FAQ for fan fiction writers), since such fan fiction tends to promote the original author and increase his/her revenue.

But other writers will sick the lawyers after you post haste. This is because some authors have sequels in mind, and fan fiction can contradict the future story line. Authors also object to their characters appearing in situations that are out-of-character for that character, or appearing in erotic scenarios.

If in doubt, ask for permission.