Frodo Baggins is the main character of J. R. R. Tolkien's monumental and mythological novel, The Lord of the Rings. He is a Hobbit, born on September 22 of the year 2968 of the Third Age (T.A.) to Drogo Baggins and Primula Brandybuck. In T.A. 2980 he lost both his parents in a boating accident. Being a young minor of twelve he was taken in by his mother's family, the Brandybucks.

In T.A. 2989, however, Frodo came under the guardianship of Bilbo Baggins, who he always calls uncle (though Frodo is actually Bilbo's first and second, once removed, cousin). Frodo was 21 years old at the time, still far short of his coming of adult age at 33. Bilbo, not having children of his own, chose Frodo as his adoptive heir. Bilbo and Frodo share a a common birthday on September 22 but Bilbo is 78 years his senior. At the opening of The Lord of the Rings, Frodo and Bilbo are celebrating their 33rd and 111st birthdays, respectively, on September 22, T.A. 3001.

Frodo was entrusted with the keeping of the One Ring when Bilbo left for Rivendell after the celebration. Frodo was warned by Gandalf that the Ring must never be used but kept secret, and safe. He did not yet know it was the One Ring. Frodo kept the Ring hidden until years later, in T.A. 3018, when Gandalf returned with more lore of the Ring. Gandalf told Frodo that he had to take the Ring away. Even though Hobbits love peace and comfort, Frodo left his village to attempt to save Middle-earth by destroying the Ring. His journey forms the primary action of the novel, when it is determined that Frodo had to take the Ring to Mount Doom (Orodruin), in Mordor, in order to destroy it.

The Lord of the Rings is primarily concerned with Frodo's quest to destroy the Ring and of the many others who seek to aid or stop him. On his quest he carried a small sword called Sting and a mithril coat under his clothes, both given to him by Bilbo.

In the German translation he is called Frodo Beutlin, in the Spanish one, Frodo Bolsón, in the French one, Frodon Sacquet, and in the Norwegian one, Frodo Lommelun.

At the end of the novel, in T.A. 3019, he returned to the Shire where he was elected mayor. After two years, he, Bilbo, and Gandalf passed over the sea and join the Elves on September 29, T.A. 3021. He had already celebrated his 53rd birthday. Having no children of his own he left his estate to Samwise Gamgee, his gardener.

In the Lord of the Rings movie trilogy, Frodo is played by Elijah Wood. In a BBC radio version, he was played by Ian Holm (who also played Bilbo in the movie version).