On a side note - does everybody's art eventually get stolen by someone on Deviant Art? Gazomg was nice enough to point me to someone using a diagram from my book and plopping it on a game piece for all to download and use.
Anytime you place your artwork anywhere on the internet there's going to be a possibility of someone walking off with it. That's the blessing and the curse of the internet. If it really bothers you, don't post anything. I have no idea who created the image I use for my avatar, random Bing search.
My TOS BSG schematics wound up on some T-shirts on eBay years ago. I called them out on it and they took them down, but at the end of the day, it's the official holders of the IP who are the only ones who can legitimately pitch a bitch - Universal in my case, CBS/Paramount in yours. None of us technically hold the rights to any of the designs in those universes. I gave up on that particular crusade many years ago.
No, but you hold the rights to your creation based on their work. You cannot legally earn money with it without a license (or permission), but no one else, can, either. Not even the original copyright or trademark holder. What it's worth to pursue those rights is up to you.