"Orc" would be trademarked for a RPG, but not a book, movie, video game ?? (Wait, is this why Game Workshop's Warhammer's are OrKs ?!)
That is why Pathfinder might have issues, despite having replaced basically all the proper names and stories ??
They don't have a trademark on the word "orc". They have IP covering a fictional "orc" species for a role playing system with some statistics and basic descriptions. This generic "orc" entity was licensed under the OGL 1.0a for anyone to use in their own games. Paizo and others based the "orc" species on the SRD.
"Ork" is a 1990s idea of a cool spelling, like "magick".
> It should be spelt ork (so the Dutch translation) in a Germanic language, but I had used the spelling orc in so many places that I have hesitated to change it in the English text, though the adjective is necessarily spelt orkish.
The OGL also defines what's protected identity, like the word "beholder" for the monster or specific book titles, and what's not, like the spell named "magic missile".
Regardless of trademark or fair use, if you agree to the OGL then you also agree to not use declared protected identity terms. For D&D, that generally means things related to their setting or branding.
There are plenty of things in D&D that would be protected by neither copyright nor trademark because they aren't even close to being original or unique to D&D: fighters, wizards, orcs, dungeons, dragons, taverns, elves, gnomes, the list goes on and on...
They aren’t Space Marines anymore, they are Adeptus Astartes.
And the Imperial Guard? Those are Astra Militarum.
They probably can't copyright the idea of a playable race of Orcs or Elves, likely can copyright (and license) particular descriptions or art of those races, and maybe can copyright the specifics about how those races work. It isn't clear, because this all hasn't been tested in court. Spells are another example - is a spell like "Lightning Bolt" with particular effects something that can be protected by copyright? It didn't use to matter much - anyone could just add the OGL to their publication and be fine - but it might start mattering a bunch more.