Bilbo Baggins is the title character and protagonist of J. R. R. Tolkien's 1937 novel The Hobbit, as well as a supporting character in The Lord of the Rings. In Tolkien's narrative conceit, in which all the writings of Middle-earth are translations from the fictitious volume of The Red Book of Westmarch, Bilbo is the author of The Hobbit and translator of various "works from the elvish" (as mentioned in the end of The Return of the King).
In The Hobbit, Bilbo Baggins, a hobbit in comfortable middle age at 50 years old, was hired in spite of himself as a "burglar" by the wizard Gandalf and 13 Dwarves led by their king Thorin Oakenshield on a quest to reclaim the Lonely Mountain and its treasure from the dragon Smaug. The adventure took Bilbo and the companions through the wilderness, to the elf haven of Rivendell, across the Misty Mountains and the black forest of Mirkwood, to Lake-town in the middle of Long Lake, and eventually to the Mountain itself. Here, after the dragon was killed and the Mountain reclaimed, the Battle of Five Armies took place.
In his journey, Bilbo encountered other fantastic creatures, including trolls, elves, giant spiders, a man who can change shape into a bear, goblins, eagles, wolves and a slimy, murderous creature named Gollum. Underground, near Gollum's lair, Bilbo accidentally found a magic ring of invisibility, which he used to escape from Gollum.
By the end of the journey, Bilbo had become wiser and more confident, having saved the day in many gruesome situations. He rescued the dwarves from giant spiders with the magic ring and a short Elven-sword he acquired. He used the ring to sneak around in dangerous places, as well as his wits to smuggle the dwarves out of the elves' prisons. When tensions arose over ownership of the recovered treasure, he tried unsuccessfully to bring the opposing sides to compromise, using the Arkenstone, a stolen heirloom jewel, as leverage. This strained his relationship with Thorin, but the two were reconciled at Thorin's deathbed. At the end of the story, Bilbo returned to his home in the Shire only to find that several of his relatives, believing him to be dead, were trying to claim his home and possessions. In addition to becoming wealthy from his share of the dwarves' treasure, he found that he had traded respectability for experience and wisdom.