"Ahh, you're forgetting Tom Bombadil my friend. He was also the oldest living being. Tom was once an ent, the first in fact, and he was so lonely that he turned himself into whatever he is now."
I always thought Tom was a Maia -- doesn't JRRT say so in one of the books? Tom is the subject of the discussion below:
http://forum.barrowdowns.com/cgi-bin...c&f=2&t=000129