His origin and nature are unknown even to the Wise. On the surface, he appears to be a short Man. He is jovial and sings often, and he describes himself thus in verse:
- Old Tom Bombadil is a merry fellow;
- Bright blue his jacket is, and his boots are yellow.
He is not truly a Man, since he may be the oldest living thing in the world. He claims to be the eldest, and to remember the first raindrop and the first acorn, and the darkness under the stars before Morgoth came. He is the "Master" of the small realm around his house, encompassing the Old Forest and the Barrow-downs. This does not mean the land belongs to him, but that he has nothing to fear from anything within his boundaries. He is unaffected by the One Ring, but has no power over it. It is speculated by Glorfindel that if Sauron conquered the world, Tom Bombadil would be the last to fall, but fall he would.
The name "Tom Bombadil" is what he is called by the Hobbits of Buckland. Other cultures know him by other names. To the Elves he is Iarwain Ben-adar, "Oldest and Fatherless", literally "Old-young Without-father". Among Dwarves and Northmen he is called Forn and Orald respectively, both meaning "Ancient" in the language of the Dwarves, the language of Rohan and the Vales of Anduin.
This ancient being must have travelled far to be known by so many, but now he has settled down with his wife Goldberry in the Old Forest, and does not go beyond the bounds within which he is "Master". Earlier in the Third Age, however, a sister of Goldberry was corrupted by the blood spilled in her spring in the wars between Arthedain and Rhudaur. He charged soldiers of Arthedain with saving this River-maid. They failed to act on this, for which Bombadil cursed them to remain in the world as unquiet dead until Naruhel, the Red-maid, as she is now known, is redeemed or destroyed.
- J.R.R. Tolkien, The Lord of the Rings, The Fellowship of the Ring, "In the House of Tom Bombadil"
- J.R.R. Tolkien, The Lord of the Rings, The Fellowship of the Ring, "The Council of Elrond"
- Chapter 12: A Dead Man's Challenge
- Chapter 13: In the Gaunt-lord's Grasp
- Arthedain's Lost Brethren
- Vessel of Purity
-  Volume I, Book 1, Chapter 8: Master of the Wood
-  Volume I, Book 1, Chapter 9: Lilies for the River-daughter
-  Volume I, Book 1, Chapter 10: Into the Barrow-downs
-  Volume I, Book 1, Chapter 11: Othrongroth
-  Volume I, Book 1, Instance: Othrongroth
-  Volume I, Book 1, Chapter 12: The Black Rider's Designs
-  Marigold
-  Defying Description
-  Synonyms for Spooky
-  Root and Rot
-  The Seed of Rot
- "Hey dol merry dol whither are you going? Tramping in the forest lands and through the rivers flowing!"