What is a listed derivative
Can I upload content by someone other than me? What about anonymous, public domain art?
Yes, but only under specific circumstances. To upload content created by someone other than yourself, you must first make absolutely certain that the content has been released under one of the allowed licenses. Furthermore, you must attribute their work to them in the Author field. Failing to do so is plagiarism. and will result in the work being removed along with a possible suspension of your account. Finally, regardless of the license the art is released under, if the artist has specifically requested that their work not be distributed from other websites, Open Game Art honors those requests and will not accept submissions of their art.
In the case of Public Domain (or CC0) art that you didn't create yourself, we appreciate if you include a link back to the source of the content. We make an effort to verify that PD content is actually in the public domain before we approve it for the archive, and it speeds things up a lot if we know where you got it. If you're the author of the work and you want to remain anonymous, just mention that in the description.
Finally, some licensed works may have specific attribution requirements that go above and beyond just listing the author of the work. If so, please list those requirements in the description.
as a courtesy to the artist, we appreciate if you include a link back to their portfolio (or the page you obtained it from) even if it's not required by the license. If this information isn't readily available and it's not required, don't worry about it.
Someone uploaded my art here without my permission. Can you take it down?
Yes, but please keep in mind that if you released your content under any Creative Commons license that allows derivative works, and the work displays shows the correct license and is attributed to you, then it is legal for that content to be here. If the attribution or license are incorrect, we would prefer to correct them rather than take the content down. However, we will remove all art at the author's request regardless of license, provided we can reasonably verify that you're the real author.
If your art is on this site and you would like it taken down, please use the Removal Request form. Be sure to include the links to any art in question.
Note that there is one case in which take-down requests will not be honored: If your art is derived from a work that was a paid commission by OpenGameArt.org, we reserve the right to archive it here. Please understand that this right is a condition of the licenses (GPL 2&3, CC-BY-SA 3) that we release the exclusive commissions under.Source: opengameart.org