hmmmm. good question. off teh top of my head, i would say that gollum would have been intended to be one of teh (to my mind) numerous unexlained things, kind of like the stone-giants. but that is just inisial reaction. i always got the sense that The Hobbit was a much less "ordered" or maybe thought-out would be better, world than LOTR. Everyone seems to be a bit mix-up (Tharanduil's folk seem nothing like what Elves "should" be like, Elrond carries red silk handkerchiefs, the Goblin doesn't instantly strike Thorin down, etc.). Maybe you could call him an imp, i don't know.
