This was long overdue, but better late then never.
Up until recently, people would be able to file a report under "My work used" if their work was stolen on deviantART.
Now, that report system has changed, first party copyright reports can now be filed under "My Intellectual Property" giving you, instead of a form to fill out, a link to the updated form asking you to fill out a DMCA report.
The DMCA hyperlink "File a DMCA Notice"
After clicking the hyperlink described in the subscript, you'll need to click ether "Me" or "A company, client, or organization I represent", file out the necessary information.
After clicking the appropriate button (The second button is roughly similar)
After filling out the report, click "Submit Notice"
Q: What if I'm not the copyright holder?
Then you'll have to report the deviation in question under "Permission issues" explained in Educate Yourself: Reporting Deviations!.
Please note that third party reports are a very low priority and will take up to a couple years for it to get through!
Q: Can't I just file a DMCA report as a third party report?
You can't, this is what you will get:
Q: Is deviantART still accepting third party reports?
The deviantART staff have disabled third party reports for quite some time. So please contact the original owner if you want to report via third party.
Thank you for reading, and remember: Stay devious
how do we know for sure the original owner?
would they care? would the BBC care if someone fills their gallery full of screen shots of their shows?