In the The Hobbit by J. R. R. Tolkien, Bombur is a fat Dwarf who accompanies Thorin Oakenshield and Bilbo Baggins on their journey to Erebor. His brother Bofur and cousin Bifur also joined the quest.

"Poor, fat" Bombur is frequently described as foolish and being the last for everything. Because he counts for two, he is the last to enter Beorn's house and the last to cross the enchanted river in Mirkwood. And he makes mistakes when he is last: He tumbles with Bifur and Bofur onto Thorin when they enter Bag End last, he enters Beorn's house early than intended, and he also slips into the enchanted river (and falls asleep). He chooses to stay and guard the supplies camp while the others move up Erebor because he trusts neither mountain paths nor ropes. Later though, he is forced to use the ropes to escape the rampaging dragon Smaug.

Bombur sleeps at several key moments in the book. When he trips into the Mirkwood river, he falls under a spell that makes him sleep for days, burdening the others with his weight as they walked on. And while he is on a midnight lookout in the fortified Erebor, Bilbo promises to keep watch so that he can sleep in the warmth (Bilbo used this opportunity to sneak the Arkenstone out of the mountain). Incidentally, he was asleep when they opened his barrel after escaping the Elves of Mirkwood and also when Bilbo discovered the secret entrance to Erebor.

In The Lord of the Rings, many years later, Frodo Baggins inquires after Bombur and learns that he has grown so fat it takes six Dwarves to lift him.