I see no mention of them in the books nor on the official Rings wiki, but in the game you can find them in Angmar, Moria, and a few bits of Mirkwood. What are they? Is there anything about them in the appendices, or are they just a species made for the game?
ps. by Morrevail I mean the winged lady things that look like Lara Croft in the face. Not sure about the spelling.