He is a principal protagonist of Tolkien's The Lord of the Rings. He is also mentioned in The Silmarillion. He was a hobbit of the Shire who inherited Sauron's Ring from Bilbo Baggins and undertook the quest to destroy it in Mount Doom.
Realizing that he was a danger to the Shire as long as he remained there with the Ring, Frodo decided to leave his home and take the Ring to Rivendell, home of Elrond, a mighty Elf lord. He sold his beloved Bag End, and left the Shire with three companions: his gardener Samwise Gamgee and his cousins Meriadoc Brandybuck and Peregrin Took. They escaped just in time, for Sauron's most powerful servants, the Nine Nazgûl, had entered the Shire as Black Riders, looking for Bilbo and the Ring. They followed Frodo's trail across the Shire and nearly intercepted him.
At the Inn of the Prancing Pony in the village of Bree, Frodo met Aragorn, a Ranger of the North, who became the hobbits' guide while journeying through the wilderness towards Rivendell. The One Ring slipped onto Frodo's finger inadvertently in the Prancing Pony's common room, turning Frodo invisible. This attracted the attention of Sauron's agents, who ransacked the Hobbit's rooms in the night. The group, under Aragorn's guidance, quickly fled through the Midgewater Marshes and again escaped the Black Riders.
While encamped at Amon Sûl, Frodo was stabbed by the Witch-king of Angmar, the chief of the Nazgûl, with a Morgul-blade. A piece of the blade remained in his shoulder and, working its way towards his heart, threatened to turn him into a wraith under the control of the Witch-king. Upon reaching Rivendell, almost overcome by his wound, he was healed by Elrond; although it was said and later seen that the wound would never completely heal, as it was as much spiritual as physical.
In Rivendell, the Council of Elrond decided to destroy the Ring by casting it into Mount Doom in Mordor, the realm of Sauron. Frodo, realizing that he was destined for this task, stepped forward to be the Ring-bearer. A fellowship of nine companions was formed and set out from Rivendell. Armed with Sting, Bilbo's Elvish short sword, and wearing Bilbo's coat of Dwarven chain mail made of mithril under his clothes, Frodo travelled with his companions through Moria, led by Gandalf, who fell into the abyss there while fighting a Balrog. Frodo was heartbroken by Gandalf's apparent demise as the company travelled through Lothlórien, where Galadriel, the Lady of the Woods, gave Frodo an Elven cloak and a phial carrying the light of Eärendil to aid him on his quest.
At Amon Hen, the Fellowship was broken. Boromir, having fallen to the lure of the Ring, tried to take it from Frodo. This prompted Frodo to leave the company on his own. Sam followed Frodo, and joined him for the journey to Mordor.
Gollum, after an anguished internal debate, eventually betrayed them, leading them to Cirith Ungol, where he intended to deliver Frodo to the giant spider Shelob and retake the Ring from her leavings. Shelob stung Frodo, sedating him, but she was driven off by Sam. Believing Frodo to be dead, Sam took the Ring from him to continue the quest. But orcs from a nearby tower found Frodo and knew that he was only paralysed, not dead. Planning to interrogate him after his awakening, they carried him into to the tower of Cirith Ungol at the head of the pass.
The four hobbits of the Fellowship returned to the Shire after the coronation of Aragorn, to find it had been taken over by a gang of ruffians, led initially by Frodo's cousin, Lotho Sackville-Baggins, and then by the fallen wizard Saruman. The four travellers roused their fellow hobbits and led them in driving the ruffians out. Frodo's part in the fighting was mainly to ensure that the ruffians who surrendered were not killed.
Frodo never completely recovered from the physical, emotional and psychological wounds he suffered during the War of the Ring. He was taken ill on the anniversaries of his wounding on Weathertop and his poisoning by Shelob. He briefly served as Deputy Mayor of the Shire, but spent most of his time writing the tale of his travels. Two years after the Ring was destroyed, Frodo and Bilbo as Ring-bearers were granted passage to Valinor — where Frodo might find peace. They boarded a ship at the Grey Havens and together with Gandalf, Elrond and Galadriel, the Keepers of the Three Rings, they passed over the sea and departed Middle Earth. Having no children of his own Frodo left his estate, along with the Red Book of Westmarch, to Sam.
Bilbo and Frodo shared a common birthday on September 22, but Bilbo was 78 years Frodo's senior. At the opening of The Fellowship of the Ring, Frodo and Bilbo were celebrating their thirty-third and eleventy-first (111th) birthdays, respectively.
Frodo, like Bilbo, was considered by many others in Hobbiton to be a little odd. His interests in the outside world, fascination with Elves and faraway places (like those to which Bilbo travelled in The Hobbit) did not fit the general content personality of most Hobbits. This curiosity was also attributed to his Took ancestry. The Tooks were also famous for their adventurous nature.
Frodo was dressed in typical Hobbit-fashion when he left the Shire: knee-breeches, shirt, waistcoat, jacket, cloak. Colours such as bright green and yellow were typical for Shire-folk. He was unarmed, save for a pocket-knife.
When his little group was waylaid by Barrow-wights, the Hobbits acquired long Dúnedain daggers in the wight's treasure. These served as short-swords for the Hobbits, but Frodo's was broken when he resisted the Witch-king at the ford of Bruinen. Later, his Uncle Bilbo gave him both Sting, a magic Elven dagger, and a coat of mithril chain mail. The mail saved his life when it deflected a spear-point in the Mines of Moria.
As with the other members of the Fellowship of the Ring, Frodo received a special cloak from Galadriel in Lórien which allowed him to blend in with natural surroundings. He also received a vial where the light of Earendil, the Evenstar (And, by extension, of the Silmaril and the Two Trees of Aman) reflected.
In Ralph Bakshi's 1978 animated version of The Lord of the Rings, Frodo was voiced by Christopher Guard. Billy Barty was the model for Frodo, as well as Bilbo and Sam, in the live-action recordings Bakshi used for rotoscoping. In the 1980 Rankin/Bass animated version of The Return of the King, made for television, the character was voiced by Orson Bean, who had previously played Bilbo in the same company's adaptation of The Hobbit.
In the 1981 BBC radio serial of The Lord of the Rings, Frodo is played by Ian Holm, who later played Bilbo in Peter Jackson's film adaptation of The Lord of the Rings.
In The Lord of the Rings film trilogy directed by Peter Jackson — The Lord of the Rings: The Fellowship of the Ring (2001), The Lord of the Rings: The Two Towers (2002) and The Lord of the Rings: The Return of the King (2003) — Frodo is played by American actor Elijah Wood. The timeline in Jackson's movie trilogy is simplified and much shorter than in the novel; in the movie Frodo sets out on his adventure a few months after inheriting Bag End and Bilbo's possessions, including the One Ring. Consequently he is much less than 50 years old, and starts out the same age as his friends Sam, Merry and Pippin, when he begins his adventure. However, this portrayal is accurate; due to the influence of the Ring, Frodo is described as looking like a "robust and energetic hobbit just out of his tweens", and as such would appear to be of a similar age to the three younger hobbits.
On stage, Frodo was portrayed by James Loye in the three-hour stage production of The Lord of the Rings, which opened in Toronto in 2006, and was brought to London in 2007. In the United States, Frodo was portrayed by Joe Sofranko in the Cincinnati productions of The Fellowship of the Ring (2001), The Two Towers (2002), and The Return of the King (2003) for Clear Stage Cincinnati. In Chicago, Patrick Blashill played Frodo in the Lifeline Theatre production of The Two Towers in 1999.