Both
Tom Bombadil is the oldest, as are other Maiar and Varda listed above. The Ents came from the thoughts of Yvanna (a Varda), who is the same age as Tom Bombadil. Also, the Ents were not resistant to Saruman's evil, but Tom Bombadil was unaffected by Sauron's evil ring.
Gandalf's age is impossible to determine, but he's likely existed for at least 10,000 years, making him much older than Legolas.
The ages of his characters differ wildly; Gollum is almost 600 years old, while Elrond, the elf, is several thousand years old, and Gandalf the Grey – and later the White – is immortal (for display reasons, both are thus not mentioned here).
Gandalf is certainly older. Gandalf is one of the Maiar, and the Maiar were created before the World was created. Elrond is called “Elrond Half-elven” because one parent was elf and the other human. He wasn't born until after Elves (first) and Dwarves (second) and Men (third) had appeared in the World.
Apperently Legolas is older than Elrond : r/lotr.
That said, the people behind the “official movie guide” for The Lord of the Rings list Legolas as being born in the year 87 of the Third Age of Middle-earth, which makes him some 2,931 years old around the time of the War of the Ring, which happened over 3,000 years into the Third Age of Middle-earth.
Frodo and Bilbo were comfortable and well off until T.A. 3001. At this time, Bilbo threw an enormous party to celebrate his 111th birthday, and Frodo's 33rd, the date of Frodo's coming of age. At this party Bilbo gave his farewell speech, and made his long-planned "disappearance" and withdrawal from the Shire.
Legolas was the only son of Thranduil, King of the Elves of Northern Mirkwood.
Aragorn led the forces of the Reunited Kingdom on military campaigns against some Easterlings and Haradrim, re-establishing rule over much territory that Gondor had lost in previous centuries. He died at the age of 210, after 122 years as king.
Cirdan: All we know of Cirdan's origin is that he was a relative of Olwe and Elwe, and that he served as a lord among the people of Elwe. It's never specified whether he's older or younger than Olwe. But, Cirdan is the oldest (named/known) elf in Middle Earth (so, basically, not counting Valinor.)
Legolas Was 2,931 Years Old (in the Films)
Tolkien actually never specified an age for the bow-toting Silvan Elf.
So at the time of LOTR, Frodo as a hobbit would be 51, but as a human would be 27.9 years old.
Shelob, who is even older than Sauron, serves as a kind of guard for one of the entrances to Mordor.
Together, the two of them were known as the Blue Wizards. The one in brown was Radagast and the one in grey was Gandalf, seemingly the oldest and the least of the Order.
In fact, Treebeard may have been a first-generation Ent because Gandalf called him "the eldest and chief of the Ents." Later, Gandalf also told Aragorn, Legolas and Gimli that Treebeard was the "oldest living thing that still walks beneath the Sun.” So it's very clear that Treebeard is older than any Elf, Man, Dwarf or ...
It is later mentioned that Tauriel is a talented warrior and was therefore made leader of the Mirkwood border guards. Legolas, the son of Mirkwood's Elven king Thranduil, is indicated to be attracted to her, but as she is a lowly Silvan Elf, she does not believe herself worthy of him.
They are both elvish nobles, as Legolas is the son of King Thranduil and Arwen is the daughter of Elrond. They are both well-educated and would have known each other as the community of elves is quite small. It's likely they would have been at least friendly with one another.
The actor is suffering from Legolas Syndrome — where you accidentally get cast into a role that suits you far more than your real-life looks, leaving you with a tricky predicament after the wrap party.
Frodo came of age as Bilbo left the Shire. Frodo inherited Bag End and Bilbo's ring. Gandalf, uncertain about the origin of the ring, warned Frodo to avoid using it and to keep it secret. Frodo kept it hidden for the next seventeen years, and it gave him the same longevity it had given Bilbo.
Does Sam ever see Frodo again? Yes, Sam eventually gets to visit Frodo again in the Undying Lands after the destruction of the One Ring. Sam is among the Fellowship of the Ring members who set sail from the Grey Havens to the Undying Lands, along with Frodo, Bilbo, Galadriel, Elrond and Gandalf.
“Mister Frodo” is Sam's way of showing respect to his employer. There is no question that Sam is being respectful toward Frodo but the Shire's aristocratic hierarchy is often overlooked by readers, no doubt because Tolkien rarely mentions it.
Why did Aragorn live so long? Aragorn is not half Elf, although he is a descendant of Elros, who is half Elf (and the brother of Elrond, the half-Elf who raised him), which explains why Aragorn's life span is unusually long.
His prowess with a bow was unmatched among the Fellowship and, as J.R.R. Tolkien stated himself, Legolas was “endowed with the tremendous vitality of Elvish bodies,” as well as an inability to feel terrible hurts, which made it easy for him to travel long distances over rough terrain in only light shoes.