Dear Games Workshop,
Boy, the internet can be mean, can't it? But don't let that get you down. You ask one writer - who's breaking into the publishing industry, by the sound of it - to pull one of her E-books off Amazon because it has "Space Marine" in the title, and everyone starts thinking you're the bad guy.
You know what I say? Screw the internet, GW. Stick to your litigious guns.
Sure, it looks bad that you're picking on someone who doesn't have the money to fight back in court. But your case is rock solid. I mean, it's not like "space" is a common word used in sci-fi, right? And who writes science fiction about a futuristic army, anyway? (Except you, of course.) Even if a person had the temerity to write a sci-fi novel about a futuristic armed force, it's not like "Marine" is a common military term, right? What unique military term is this M.C.A. Hogarth (if that's even her real name...) going to steal from you next? "Uniforms"? "Tank"? "Spaceship"?
Strike while the iron's hot, GW. Trademark anything and everything you can that could possibly represent your brand name. Here are a few suggestions:
* Dwindling Fanbase
* Overpriced Miniatures
* Zero Concept of How Public Relations Work
* Needlessly Putting Skulls On Things To Make Them Look "Cooler"
* Money-Grubbing Bastards
Best of luck, GW. Now if you'll excuse me, I just heard a writer is about to start a book about a young orphan who finds out it's his destiny to save the world. You just know George Lucas and J.K. Rowling are going to want a piece of that lawsuit...