One thing I did want to mention though; I think the major part of the distinction that's made between using fanart and using canon/pro art from the actual show/comic/what have you is this: when you have work that's recognizably from the original copyrighted work, everyone involved knows that it's not YOUR work, you're just using it. But when you use fanart, there tends to be an inherent assumption (unless you say otherwise) that the fanart is your own. I think what bugs a lot of people is that if a person using the fanart doesn't credit it, the viewers of the new work are probably going to be confused as to its origin and think the fanart was done by the person presenting it as part of their new work. And that rankles; understandably, I think.
That said, I think it's still wrong to use the pro work without crediting. Because there's also the factor of, if you did the work you should get credit for it. But at least with using pro work there's not that implied ownership of the original work.
no subject
One thing I did want to mention though; I think the major part of the distinction that's made between using fanart and using canon/pro art from the actual show/comic/what have you is this: when you have work that's recognizably from the original copyrighted work, everyone involved knows that it's not YOUR work, you're just using it. But when you use fanart, there tends to be an inherent assumption (unless you say otherwise) that the fanart is your own. I think what bugs a lot of people is that if a person using the fanart doesn't credit it, the viewers of the new work are probably going to be confused as to its origin and think the fanart was done by the person presenting it as part of their new work. And that rankles; understandably, I think.
That said, I think it's still wrong to use the pro work without crediting. Because there's also the factor of, if you did the work you should get credit for it. But at least with using pro work there's not that implied ownership of the original work.