No, Tom Bombadil could not have defeated Sauron. As
The consensus among the Wise is that, even weakened and without the Ring, Sauron is more powerful than Tom Bombadil. Power to defy our Enemy is not in him, unless such power is in the earth itself. And yet we see that Sauron can torture and destroy the very hills.
Originally Answered: Why doesn't Sauron fear Tom Bombadil? Because Tom's power is limited to the area close to his home, in and near the Old Forest. The Elves of Rivendell speculate whether he could defy Sauron, and in their opinion, he could not.
According to Gandalf, if Sauron got the Ring, even Bombadil would fall, but he would be “last as he was first.” The Lord of the Rings (creative franchise): Who exactly is Tom Bombadil?
More powerful than Gandalf and more ancient than Galadriel, Tom Bombadil is actually Lord of the Rings' most powerful being. When it comes to powerful beings in The Lord of the Rings, characters such as Gandalf, Saruman, Galadriel and Sauron are discussed at great length.
14 Tom Bombadil, The Joyful
He is a joyful soul, and this hides an immense well of power. No earthly strife seems to trouble him, and he is immune to the power of the Ring. Such propensity aligns Tom with the Valar or perhaps something greater, and Gandalf would never be able to overpower him.
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.
Proclaimed to be "the oldest in existence," Tom Bombadil was apparently immortal and possesses a range of enigmatic powers able to give full control over his domains, seen by Goldberry that described Tom as being "Master of wood, water and hill". He was also referenced as being impossible to capture or imprison.
When Frodo shows Tom Bombadil the Ring, he amazes the Hobbits by putting the Ring on without disappearing. The reason that Tom Bombadil is not subject to the power of the Ring is that he really, truly does not desire power or ownership over any one thing.
There's no shame in this (despite what some hardcore corners of the fandom say), but it does leave these movie-only Middle-Earth fans vulnerable to misconceptions about Tom Bombadil's power. He is incredibly powerful and is immune to the effects of the One Ring. He is not, however, more powerful than Morgoth.
The Tolkien scholar and philosopher Gene Hargrove argued in Mythlore in 1986 that Tolkien understood who Bombadil is, but purposefully made him enigmatic. Nevertheless, Tolkien left clues that Bombadil is a Vala, a god of Middle-Earth, specifically Aulë, the archangelic demigod who created the dwarves.
Sauron was first afraid of the idea of Aragorn, as a pretender come to claim his ring. Then after their contest for the control of the Orthanc Palantir, Sauron was genuinely afraid of Aragorn, the man. Even though he was 'just' a man Aragorn was the focal point of all things that opposed Sauron.
Gandalf clarified that it wasn't so much that Tom had power over the Ring, but that the Ring had no power over Tom. “He is his own master. But he cannot alter the Ring itself, nor break its power over others.
Eru Ilúvatar is the creator of Middle-earth and all its inhabitants. He possesses infinite power and is responsible for the destiny of all beings in the world. In conclusion, Middle-earth is home to a wide variety of powerful and magical beings, each with their own unique abilities and strengths.
God is the most powerful entity in Tolkien's Lord of the Rings universe. The Elvish name for him is actually Eru Ilúvatar, meaning “the one, father of all.” So the question becomes: Who is the second-most powerful being? Originally, it was Melkor, “he who arises in might,” the most powerful of the Ainur (or angels).
Through all of Tolkien's extensive legendarium, the nature, purpose, and history of Tom Bombadil remains almost entirely unknown. Nevertheless, the mysterious Tom Bombadil is one of few characters from The Lord of the Rings old enough to appear in The Rings of Power.
Sauron would have destroyed Tom Bombadil, no question asked. Tom Bombadil is not “impervious” to Sauron power, he is not immune to violence and physical power, he is immune to the corruption of the rings and other matters of domination. This is an element of nature not of power.
Bombadil could have been created as a side-effect of the Music of the Ainur and that would explain why he was there in the beginning. His Elvish name "Eldest Fatherless" can support this notion: since he is only a part of creation, he has no "father", while the Ainur have (Eru).
His exact race is not known, and he remains mysterious—although with some apparent magical and spiritual abilities. Tom Bombadil lived with his wife, Goldberry, just east of the Shire in the Old Forest. He has a few titles, like The First and Eldest.
Sauron nor Morgoth are the most powerful in Tolkien's world
In Tolkien's lore, the most powerful being is Eru Ilúvatar, which means "the one, father of all” in Elvish. The author purposefully created him to reflect his Judeo-Christian beliefs. Eru is God, while Morgoth is the Devil, according to Biblical references.
No. That's nearly impossible for a number of reasons. (1) We know that the Blue Wizards came to Middle-earth at some point in the Third Age* to help the Free Peoples in their fight against Sauron with their powers and wise counsel. Tom Bombadil lived in Middle-earth since its foundation—both he and others explain that.
Outside his own borders, he had no great power he could bring to bear. And he wasn't the same kind or order of being as Sauron. It's stated in the text that Tom doesn't even have the power to defy Sauron, let alone defeat him, “unless such power is in the earth itself”.
Tom's absent mindedness might lead to a forgetting of the cosmos with catastrophic consequences. As Gandalf says of Bombadil at the Council of Elrond, “If he were given the Ring, he would soon forget it, or most likely throw it away. Such things have no hold on his mind.
Q: What Happened to Tom Bombadill after the Destruction of the One Ring and the Fall of Sauron? ANSWER: We know that Tom continued to live quietly in his little country at least until Gandalf visited him in 3019.