The most common theory is, therefore, that Bombadil is just a "rogue" Maia who perhaps stayed behind and did not follow the other Ainur at the Breaking of the World. In contrast to the seven Valar, the Maiar are an unknown number, so it's easy to associate Tom with them.
Tom Bombadil was not Ainur, as far as we can tell, although many will claim that he was. People claim that there were only Ainur (Valar and Maiar) from the very beginning. But Tolkien was never so adamant about these things.
In general, it is considered as accepted the theory that Tom is one of the Ainur, angelic beings who shaped the earth. In fact, Robert Foster's The Complete Guide to Middle-earth describes him as "a Maia 'gone native'".
Perhaps the most far-fetched theory yet states that Tom is not really the jolly old being we see, but in fact, something eviler, and much more powerful, than Sauron and many other characters.
As Johnston summarizes: What we know about Bombadil is that he is a powerful and ancient being, older than Gandalf and older than the elves, and he has no interest in “trinkets” that are used to dominate others. Although he is aware of evil, he has no fear of it.
Although Tom would fall if the Dark Lord wins ("Nothing would be left for him in the world of Sauron," Ibid.), he would probably be "the Last as he was the First" (Rings, 1:279).
Many Lord of the Rings fans also say Tom Bombadil is actually the most powerful character in all of Middle Earth, due to his apparent immortality, ability to completely resist the Ring, power over his domain, and knowledge that comes from living since the beginning of time.
It doesn't say anywhere that the Ring tried to possess Tom Bombadil and that he resisted. The Ring simply has no effect on Tom, and that's probably because Tom is a being out of space and time. He is a complete anomaly as well as an incongruity. The laws of Middle-earth almost don't apply to him.
For one thing, Gandalf tells us there are only five wizards in Middle Earth: the Brown Wizard, Radagast, who is definitely not Tom; Saruman the White who shows up elsewhere in Lord of the Rings; the two Blue Wizards, Alatar and Pallando, who went into the east and have not been heard from again; and, of course, Gandalf ...
Some have theorized that Bombadil was a member of the Istari, powerful angelic beings, but his behavior and choices also make that idea unlikely. Other readers wonder if Bombadil might have been one of the Ainur. Ainur are best understood as descendants of the gods and consist of Valar and Maiar.
The great Elrond, who lived in the Second Age, suggests as much when he refers to Tom as a "strange creature." Elrond's knowledge of the Ainur suggests he would've recognized Bombadil if he were one of them, so it's strange that even the wise old elf can't guess at Bombadil's nature.
Gandalf says, in response to Frodo's query of how well Bombadil is getting along, that Bombadil is "as well as ever", "quite untroubled" and "not much interested in anything that we have done and seen", save their visits to the Ents.
Initially, when looking at Beorn and Tom Bombadil, it is easy to see their differences. Beorn is a man, while Bombadil is not. Beorn is physically a very imposing figure, whereas Bombadil is comical in his appearance. Bombadil is married to Goldberry, and this marriage is a very important aspect of his existence.
But there's actually a long-standing fan theory of the original books, which, if true, quietly means Tom Bombadil was in the movies all along — in his true form as the Witch-king of the Nazgûl. The twist seems outlandish, especially considering Bombadil's overtly benevolent nature in Tolkien's work.
Basically, he's a Christ figure I think. Not Eru by title, but an appearance of him, like Jesus. Frodo asks Goldberry who exactly Tom is. She simply replies, "He is." Jesus says this himself in the gospels, "before Abraham was, I am." The Jews wanted to stone him because he was declaring himself to be God.
The Ring cannot effect Tom Bombadil because he is outside the whole issue of Power and Domination; Tolkien uses Tom as an allegory that even this intense struggle between "good and evil" is only part of the whole picture of existence.
Peter Jackson has explained his decision to omit Tom Bombadil from The Lord of the Rings movie trilogy, claiming that the character's contribution to The Fellowship of the Ring bore little relevance to the overall plot and did nothing to advance the main story - unlike Lord of the Rings' Istari, to which Tom Bombadil ...
Given these bits of information, it seems like within his realm, Bombadil would have been able to defeat the Nazgûl or at least banish them. Outside his realm, however, he wouldn't have been quite as effective in a fight against them.
Tom Bombadil's strength lies not in physical prowess but in his unwavering goodness and connection to nature. He is a creature of immense antiquity, predating even the likes of Sauron. His power is unobtrusive, but it distinguishes Tolkien's understanding of strength versus might.
She also resisted being offered the ring of power by Frodo following his vision in the mirror of Galadriel, an immense test given the ring's seductive powers. Yet Gandalf's power level exceeds even that of Galadriel, as shown by his rebirth in the Two Towers.
Sauron with the Ring would have been able to defeat Tom. “In the end he will fall, Last as he was First, and then Night will come.” They decided that Bombadil would be “a most unsafe guardian, likely to lose it or throw it away.” The Ring had so little effect on him. He WAS a bit of a space case, after all.
In Tolkien's Letter 144, he emphasized that Tom Bombadil represents something important. That is the idea of pure good without it's rivalry against evil. Purity in goodness without understanding or caring to understand evil. Tolkien wrote the story about good vs.
Tolkien himself rejected the idea that Bombadil is God, and wrote to his publisher that Tom represents “the spirit of the vanishing landscapes of Oxfordshire and Berkshire.” I think this is a casual brush-off. Tolkien acknowledged that Tom Bombadil was a mysterious figure who defied easy Middle-Earth categories.
