[lathspell]

As for the hobbit I would go for Bilbo. He is the greatest hero in the, going with some dwarves on an adventure of which you know that there's a dragon waiting for you at the end. And his actions in Mirkwood and the Elven-Kingdom were heroic.
LotR - Almost all of the important characters are hero's, but if I had to choose one it would be Aragorn, because he traced Gollum and had the important part of gaining the kingship of Gondor.
Silmarillion - I've always thought of Beren, Luthien, Hurin and his son Turin. But in my opinion Earendil is the greatest hero because of his sailing the oceans to Valinor to save ME. I even think of him as greatest hero of all ages as I've said elsewhere.

Galadriel indeed was important in the history of ME, but I don't think she was the hero in it. I guess she is the most powerfull elf, or even most powerfull of all things (except the DL) in LotR.