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).
Frodo Baggins is a fictional character in J. R. R. Tolkien's legendarium, and primary character of The Lord of the Rings. Frodo is a hobbit of the Shire who inherits the One Ring from Bilbo Baggins and undertakes the quest to destroy it in the fires of Mount Doom. He is also mentioned in Tolkien's posthumously published works, The Silmarillion and Unfinished Tales.