In commenting on a story in the showcase that included Orcs, I offered the following... well... okay, it's a rant. But I also think it's an important talking point for fantasy writers and I wanted to to put it out to the group.
A story about a knight or that has knights in it isn't derivative because of the documented historical precedent and the vast body of work that has made the concept an archetype of the genre.
A story about vampires isn't derivative because of the extensive cultural folklore that spans the globe that supports it and the vast body of work that has made the concept an archetype of the genre.
Orcs are Tolkien's creation (yes, Lief, they are. He may have drawn from mythology, but the contemporary awareness of the "orc" is rooted squarely with Tolkien), a metaphor for the cruel brutality he saw in the world. D&D took Tolkien's creation and turned them into 1 hit-die targets for low-level player characters. While there are many D&D novels that feature orcs, they all reference back to a single source - D&D - which in turn points back to Tolkien.
Consequently, ANY work that features orcs ultimately will be associated with and over-shadowed by D&D and Tolkien. It can't stand on its own merit because as soon as the reader sees "orc" they will think of either Gary Gygax or Viggo Mortensen (or possibly Ian McKellen). What they WON'T be thinking of is the AUTHOR's story, and whatever tale they are attempting to tell will essentially be Tolkien fan fiction.
Not that there's anything wrong with Tolkien fan fiction. It's a great world and a wonderful opportunity for a writer to hone their craft in a world where the original writer has done most of the heavy lifting. Go for it!
I'm not suggesting anyone remove fantasy elements from a fantasy story. I'm suggesting that, if you - as a writer - need a race to embody the archetype of cruelty and brutality in your fantasy world, that you create one based on YOUR story, not someone else's.