Well then the answer must be Ar-Gimilzor. You could have said a little bit more about what he did to narrow down the answer a bit more. All I really had to go on was that he was a cruel King of Numenor that "moved many faithful folk from the west." But it was a good riddle nonetheless. Now I'm going to think of and write a riddle about a little known character of Middle Earth. I'll have it up here in a little while.