[Morsul the Dark]

here's a unique theory

http://flyingmoose.org/tolksarc/theories/bombadil.html

also on another site;

Tom Bombadil is from Wonderland.
He just plain doesn't fit in Middle-earth; he's much more "fairy-tale" than anything else that exists, with magical powers and implied incredible age despite being apparently human. His bit of the story is a cheerful diversion from the main plot, and almost seems to belong to another tale altogether.
Alternatively, he's from Oz.
Or, he is The One, aka Eru aka Ilúvatar. The Ring has no affect on him whatsoever, and in fact, he makes the Ring disappear briefly! When Frodo puts on the Ring, it is said he is putting one foot in the Wraith world and if he wears it too long, risks becoming a wraith. But the "wraith world" is not necessarily an evil place, for, because of the Ring, Frodo is able to see Glorfindel's "other side" the side that exists in the "wraith" or "spirit" world when Glorfindel goes all badass at the Ford of Bruinen. Tom does not disappear when he puts on the Ring, because the Ring has nowhere to pull him to, he already exists totally on "the other side" as the One. In a way, by making the Ring disappear, Tom is pulling the Ring all the way over to "the other side" with himself. Gandalf remarks at the Council of Elrond to the affect that it is notsomuch that Tom has power over the Ring as that the Ring has no power over him, which fits in with Tom as the One, since a creation cannot be higher than the Creator, but the One being a Creator that doesn't muck around with the free will of his creations (but doesn't mind extending a helping hand every now and again). Even Tom's habit of incessant singing fits this theory.
The whole idea was Jossed by Tolkien in 1954, as he has stated in his letters that The One has no incarnation in Middle-earth. This naturally depends on how heavily you accept the Word Of God.
Or, he is Aulë the Smith. Aulë is unique among the Valar in being fonder of life in Middle-earth than in Heaven, as the god of created objects he would naturally have power over the Ring, and he is romantically involved with an earth-mother goddess who is described in similar terms to Goldberry. Only he has the means, motive and opportunity.
A longish essay (on painful background, unfortunately) on this premise is here.
Oromë was like that too, and I could more easily imagine him as Bombadil than Aulë, whose fascination with created and non-living things just doesn't fit with Tom's close-to-nature lifestyle. Also, his nature as the "Eldest" being on Middle-earth would support this, as, if this troper remembers correctly, Oromë was the first of the Valar to set foot on Middle-earth and certainly the only one to remain there for any length of time.
Or he's one of the Maiar, since Gandalf seems to view him on equal terms, not as a servant would his master.
Tom Bombadil is Santa Claus, and Sauron is the Grinch. Tom, who of course is really the spirit of Middle-earth incarnate, switched rings on Frodo, claiming the Ring for himself. At the proper moment, he used the Ring to throw down Sauron, reducing him to powerlessness. Over the long centuries that followed, the Ring darkened his heart until he became Santa Claus, lord of greed, bringer of strife. It's all explained here.
Or maybe he was just hanging around Middle-earth during that hundred-year-or-so period when he was kept out of Narnia by the White Witch.
Tom Bombadil is the Witch-king of Angmar. Explained here.
As strange as that theory is, it does look like it has textual backup.
Tom Bombadil is Thomas Covenant. He's just enjoying a holiday after his fairly harrowing adventures in a foreign land. What, the name wasn't a hint?
Tom Bombadil is the Green Man from folklore, the manifestation of the British/Shire countryside. At least metaphorically.
That's the what Word Of God say he really but Tolkien just put him the story to mess with readers' heads.
Tom Bombadil represents the reader. You are Tom Bombadil. He can see Frodo when he's wearing the ring, which has no power over him and Elrond says a world ruled by Sauron would have no interest for him but he could not take the ring himself.
Isn't anyone going to say he's a Time Lord?
He's actually an incarnation of Suzumiya Haruhi, when she was going through an obsession with medieval fantasy.
Clearly Tom is actually a Refugee From Discworld. You know it's true