Both
The Ents appear in The Lord of the Rings as ancient shepherds of the forest and allies of the free peoples of Middle-earth during the War of the Ring. The Ent who figures most prominently in the book is Treebeard, who is called the oldest creature in Middle-earth (a description also given to Tom Bombadil).
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.
Treebeard is described as the oldest of all living things. Celeborn and Galadriel would be the oldest among the elves both having been born in the Years of the Trees. So there are a lot of characters in Lord of the Rings who are thousands of years old.
Gandalf's age is impossible to determine, but he's likely existed for at least 10,000 years, making him much older than Legolas.
He died at the age of 210, after 122 years as king. The graves of the hobbits Merry and Pippin (who had died in Gondor 58 years earlier) were set beside his. He was succeeded on the throne by his son, Eldarion. Arwen, heartbroken by the loss of her husband, died shortly afterwards in Lothlórien.
Long story short, this means that Legolas, as the son of Thranduil, would be a Sindar Elf by blood. However, he (along with the rest of the Fellowship) seems to consider himself a Wood-elf (one of the Silvan Elves), as they are his people.
I'm reading the fall of Gondolin and at one point the citizens of the city are fleeing over a plain, they are led by Legolas Greenleaf (page 100 in my book). At the same time the son of Tuor and Idril Eärendil, is 8 years old, he is also the father of Elrond.
God is the most powerful entity in Tolkien's Lord of the Rings universe. The Elvish name for him is actually Eru Ilúvatar, meaning “the one, father of all.” So the question becomes: Who is the second-most powerful being? Originally, it was Melkor, “he who arises in might,” the most powerful of the Ainur (or angels).
Eru is introduced in The Silmarillion as the supreme being of the universe, creator of all existence, including the world, Arda, and its central continent, Middle-earth. In Tolkien's invented Elvish language Quenya, Eru means "The One", or "He that is Alone" and Ilúvatar signifies "Allfather".
The protagonist stands as the oldest of the four hobbits who accept the task of taking the ring to Mount Doom where it was created. Samwise Gamgee, the famed gardener of Frodo is surprisingly younger, at the age of 38.
Without a doubt, the most powerful wizard in Middle-earth is Gandalf the White. While Gandalf was always a reasonably powerful wizard in his own right, facing off against the Balrog in the Mines of Moria, a battle that took ten days and resulted in the mutual demise of Gandalf and the Balrog.
Legolas was portrayed by Orlando Bloom. In the "official movie guide" for The Lord of the Rings, a birthdate for Legolas is set to 87 of the Third Age. This would make him 2931 years old at the time of the War of the Ring.
Gandalf explained that it did not grant new life, but that the possessor merely continued until life became unbearably wearisome. The Ring did not protect its bearer from destruction; Gollum perished in the Crack of Doom, and Sauron's body was destroyed in the downfall of Númenor.
While there is no official answer for why Bilbo and Sam were able to be rid of the Ring without too much issue, there is a lot of supporting evidence that suggests it was partially due to their inner morality, as well as partially because of the Ring choosing its own path.
He had already celebrated his 131st birthday, becoming the oldest Hobbit in the history of Middle-earth. As a mortal, he died in the West. While sailing west, Bilbo composed a last poem looking back on Middle-earth in farewell.
Rockseer Elves or Deep Elves
"Rockseer elves are the rarest of all elvenkind. They are far taller than most of their kin, with a few reaching almost to eight feet in height. An average weight for a Rockseer is between 120 and 140 pounds, with little gender difference.
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.
Haldir leads a regiment of Elven archers from Lórien to the Battle of Helm's Deep, where he is eventually slain, along with most of his archers.