Frodo Baggins was the son of Drogo Baggins and Primula Brandybuck, but was adopted by Bilbo Baggins, his uncle (or perhaps his cousin, which of these is disputable) in 2980. Frodo was a Ring-bearer, an Elf-friend, and a true hero. He is perhaps the single-most important person of the entire Third Age. In 3001 Frodo inherited the One Ring.

In 3018, by the advice of Gandalf, Frodo fled the Shire and went to Rivendell with Aragorn, Sam, Merry, and Pippin to escape the Ringwraiths. On Weathertop he was attacked by the Black Riders, and nearly slain by the Lord of the Nazgûl. He reached Rivendell upon Asfaloth where he was healed by Elrond Halfelven, and then attended the Council of Elrond, before embarking upon the Quest of Orodruin. The Quest was completed in 3019 when Gollum attacked Frodo is Sammath Naur, for Frodo had claimed the Ring for his own, and bit off his ring-finger. Gollum and the Ring were both destroyed when Gollum toppled into the Crack of Doom.

Frodo returned to the Shire in 3019, and for a brief time was the mayor of Michel Delving, but he could not keep the job for he was constantly tortured by the poison of the wounds of both Shelob and the Nazgûl Lord. Thus he sailed over the Sea at the End of the Third Age with the last of the Ring-bearers save Sam, leaving Bag End and all his belongings to his best friend and servant, Sam.

Frodo wrote an account of the Quest of Orodruin and the War of the Ring in the Red Book of Westmarch.

Frodo had always been a quite different hobbit, being thin and loving stories and news of far off lands. Frodo was relatively unaffected by the Ring, save that he did at the end fall victim to it, and he aged slowly because of it. He knew Sindarin and possibly some Quenya and had a great ability of pronouncing foreign languages. He had few friends of his own age group; his friends included Bilbo, who was considerably older, and Sam, Pippin, and Merry, who were somewhat younger.