For years, there have been stories about Games Workshop being trademark bullies and sending threats to people who use the term "space marine" in connection with games. But now that they've started publishing ebooks, Games Workshop has begun to assert a trademark on the generic, widely used, very old term "space marine" in connection with science fiction literature.
MCA Hogarth, an author who has published several novels in ebook form, has had her book "Spots the Space Marine" taken down on Amazon in response to a legal threat from Games Workshop. She could conceivably fight the trademark claim, but that would cost (a lot) of money, which she doesn't have...
.. Games Workshop's strategy is to make "space marine" less generic by launching high profile, bullying attacks on everyone who uses it, so that there will come a day when people hearing the phrase immediately conclude that it must be related to Games Workshop, because everyone know what colossal dicks they are whenever anyone else uses the phrase...