Welcome to my home-away-from-home in Middle-earth. Here you may call me Ertur (click here or here for Middle-earth name dictionaries).

One of the most interesting mysteries of J. R. R. Tolkien's Middle-earth is the character of Tom Bombadil. There have already been a number of excellent essays written on this topic (click here for Gene Hargrove's essay on the matter and links to others). There will almost certainly never be any firm answer, but I do have some different thoughts on this matter that I would like to share.

Who or what are Tom Bombadil and Goldberry?

It is quite clear that they are not human, elf, dwarf, or hobbit, nor any of Morgoth's beasts. That leaves us with three possibilities: Vala or Maia, children of the Valar or Maiar, or something not otherwise described by Tolkien. Tolkien very clearly leaves the door open to the third possibility by writing, in the Valaquenta, “... the Valar and the Maiar, or of any other order that Ilúvatar has sent into Eä.” Given the context, I don't believe that this refers to the elves or to men, but to some other, more powerful beings, probably of less power than the Maiar, but possibly of a different nature, tied more closely to Arda.

Of the Valar, the closest in description seem to me to be Oromë and Vána. Gene Hargrove suggested that Oromë, as “a hunter of monsters and fell beasts”, would have hunted down all of the barrow-wights long ago, but I don’t think that “monsters and fell beasts” necessarily encompasses spirits from Angband haunting the barrow-downs. The biggest problem that I see with the Valar theory is that by the end of the third age, some among the elves should have developed some suspicion about his identity. Another difficulty is explaining how Goldberry, as a Vala as well, is the river-woman's daughter.

The most common argument against the Maia hypothesis is that Gandalf and Saruman seemed to be affected by the ring, but this argument does not hold up under scrutiny.
First, the Ainulindalë states that the powers of the Maiar varied, and that some were nearly as powerful as the Valar. “And the Valar drew unto them many companions, some less, some well nigh as great as themselves…” So, we should not be judging the abilities of one Maia by the abilities of another.
Second, these arguments are based primarily on Gandalf’s statements that he will not take the ring because he fears that the temptation of using it might be too great. We don’t really know (and Gandalf probably doesn’t know either) if a Maia would be drawn to its power the same way that Gollum, Bilbo, and Frodo were. Furthermore, we don’t know what constraints the Valar have placed on Gandalf’s mission. It is my understanding that the Istari were sent into Middle-earth to help its inhabitants rid the world of Sauron's menace. This suggests that Gandalf’s actions may be restricted by the Valar, and thus some of Gandalf’s words may simply be a cover for the fact that he cannot take too direct a part in these affairs.
Third, it seems quite clear that Sauron himself did not become invisible when he wore the ring, since Isildur was able to cut off the finger that wore it. There we have evidence of at least one Maia who is not affected by the ring’s power of invisibility.
Given these three points, it seems perfectly reasonable to propose that Tom Bombadil could be a Maia.

Another point of contention has been Tom's great age. He says that he was in that forest when the elves first came westward, indeed even before the arrival of the Dark Lord (Melkor) in Middle-earth. In the Silmarillion, there is no clear statement of the order the Valar arrived on Arda, but the Ainulindalë does suggest that Melkor left the rest of the Valar to their work in Arda for some time, and returned, in physical form, after the rest of the Valar had themselves taken physical form of their own. It is certainly possible that Tom, if he is a Maia or Vala, was in fact in Arda before Melkor, or he could be referring to Melkor’s arrival in physical form.

There is no reason to assume that Goldberry is necessarily of the same order as Tom, nor as old as him. If Tom was a Vala, then it would be likely that Goldberry would be his spouse. However, If Tom is a Maia or of some other order, then the possibilities for Goldberry are much wider. She could, of course also be a Maia or of one of the other groups alluded to. In addition, we should consider the possibility that she could be the offspring of a Vala or Maia. If she were related to Ulmo or a Maia follower of Ulmo, it could explain why she is know as the River-daughter or the River Woman's daughter.