>>632779
I was always under the impression that fan art could be considered derivative work, which means it would thereby belong to the holder of the copyright or trademark.
However, most copyright holders tend to turn a blind eye to the act either because the fan art does no harm to their brand or because enforcing it on the Internet would be near impossible.
It's somewhat of a gray area for US copyright law and rarely tested. Personally, I look at it this way: if I drew a picture of, say, Minerva Mink and started to sell it to people, Warner Brothers wouldn't allow it and would very likely win any resulting legal battle. But, if I draw the same picture and don't sell it, that doesn't make it magically legal in my view. It would just seems to make it harder for Warner Brothers to come down on me. (I base this on the idea that if you pirate something, it doesn't matter if you made a profit, it's still illegal.)
But, as I said, copyright holders usually turn a blind eye to fan art and fiction. I'd love to see the legal battle that would ensue should a copyright holder produce something based on fan art or fiction. Could the fan sue and win?