Plagiarism? Or Simple Coincidence?

[Lord Halsar]

I'm not meaning to point fingers with this thread, and I'm not looking for trouble, but it has come to my attention of several occurrences in both literacy and other sources that catch my suspicions of plagiarism.
The first is a scenario in the Inheritance Trilogy by Christopher Paolini. A mortal man named Eragon (sound familiar, Aragorn?) becomes infatuated to an elf princess named Arya (coincidence thy name is Arwen). Urgals-Orcs? Kull(correct me if that is misspelled) and Trolls? I'm seeing some similarity(even though the plot of the story itself seems more like that of Star-Wars than LotR to me).
The next is in J.K. Rowling's Harry Potter (again, not trying to raise trouble, just making a point). Giant spiders living in a dark forest? the name Longbottom is self-explainatory I hope.
And the last, is in a massively popular online game that many have grown to know and thrive on. World of Warcraft. Lich-King who was once a mighty Lord of men? Witch-king who was once a king of men. both of which ruled a frozen kingdom in the north of their world. And the name Anduin of the great river is also the name of the king of men who rules from the last bastion of human power in WoW.
Are all of these thing mere coincidences, accidents of all sorts? Or were they intentionally written and sold with full knowledge of the similarities that were already existent in the works of our beloved J.R.R.T?
For a final time I say, I am not trying to raise anger in anyone. Just saying how I see it, and I am not trying to discredit the authors and game that I have mentioned. I also realize that ther could indeed be much more to this list, but this was all that I could remember on short notice. Perhaps others will contribute to it....