In the first book of J. R. R. Tolkien's fantasy epic The Lord of the Rings, Frodo and his company meet Tom Bombadil in the Old Forest. He is a quite mysterious figure living far from any settlement with his wife, Goldberry. He speaks in stress-timed meter. His appearance is only brief, but behind Bombadil's simple facade there are hints of great knowledge -- he can see the Ringbearer when invisible and is unaffected by wearing the Ring himself. Gandalf says this is because the Ring has no power over him.
Bombadil's mythological origins in the cosmology of Middle-earth have puzzled even erudite fans. Speculative ideas about his true nature range from simply a wise Elven hermit to an angelic being (a Maia or Vala), to the creator, that is, God, who is called Eru Ilúvatar in J. R. R. Tolkien's mythology. Tolkien explicitly denied this last possibility.
As to the nature of Bombadil, Tolkien himself said that some things should remain mysterious in any mythology, hidden even to its inventor. He placed the fate of the Entwives in this category, as well as the Cats of Queen Béruthiel, although hints of the latter story have emerged in posthumously released materials.
It is clear, though, that Bombadil was not in Tolkien's conception part of Middle-earth from the start; he was created in honor of a doll belonging to his children, to whom Tolkien told stories about Tom Bombadil. These predate the writing of The Lord of the Rings. In recent film and radio adaptations of the story Bombadil is notable by his absence.