The Older Immortal

In a group of immortals, (or very Long Lived people) there will be at least one who is considerably older than any of the others. If most of them are 200 years old, one will be 600, or 1000. If most are 600 or 1000 years old, one will be 2000 or 3000 years old. And so on, possibly to Time Abyss status. These are The Older Immortal.

Examples of The Older Immortal include:

Anime/Manga

In the Fullmetal Alchemist manga, out of all the homunculi, Pride is the oldest and most powerful at over 300 years old.
- In the first anime, this role falls to Envy.
All the characters in Axis Powers Hetalia are old, but most are maybe a thousand. China is over four thousand.
In Hellsing, Alucard is the original Dracula who's been around for centuries, and basically everyone else is a WWII vet or younger.
In Bleach, Head Captain Yamamoto is over 2,000 years old; with the possible exception of his students, the next oldest shinigami only have a few centuries to their name.
- Since he looked the same back then and neither of his students have visibly aged much in 2,000 years, given the apparent aging speed of Shinigami it is likely that he is much, much older than that.
Baccano! has the original immortals who became immortal in 1711, and then a newer batch in 1930. Most of the 1930 ones are in an organization together, but one of the senior members of said organization is from the 1711 group.
- Later in the novels, one character (Renee) is introduced who's been immortal even longer than the 1711 group; how much older she is still hasn't been revealed.
The Lifemaker in Negima is over two thousand years old as compared to Evangeline being around six hundred and Zect being 'a couple of centuries or so' old. Albireo's relation to this trope is a little tricky, as he's older than Evangeline, but it is unclear by how much. He claims to be "the oldest one present" when in the presence of both Evangeline and the Lifemaker, though.
Normal vampires live a few hundred years in Trinity Blood. Abel and the other Crusnik (his brother Cain and sister Seth) live millenia and are apparently immortal barring violent death.

Comic Books

In Neil Gaiman's The Sandman: Brief Lives, Bernie Capax is killed in a freak accident while walking down the street in the current day while reminiscing about meeting the Marquis de Sade, talking with Freud, and the smell of Mammoths. When he meets Death he is upset because he is still not yet "done" with life, but he tries to console himself with how long he managed to last. She is unimpressed, telling him - "You lived what anybody gets, Bernie. You got a lifetime. No more. No less." Bernie's feat is shown to be genuinely unimpressive compared to some others, as it is revealed that there are around 500 beings still alive that remember the human civilizations from before the Dinosaurs, and 70 or so still around that were born before the Earth formed from gas and dust!
- Obviously there are also the Endless, Lucifer and the other angels, who all hail from the beginning of time, or even before it.

Death: "When the first living thing existed, I was there, waiting."

DC Comics has the Guardians of the Universe, who are members of what may have been the first sentient organic species in the universe. Individual Guardians, along with their kin the Zamarons and the Controllers, are billions of years old.
Marvel Comics has Galactus, who is the sole survivor of the previous universe that existed before the Big Bang. Also, the Elders of the Universe, each of whom is the last living member of one of the first races to evolve. Word of God is that Mr. Immortal (who is absolutely immune to death) of the Great Lakes Avengers will live to see the end of the universe, implying that he'll take Galactus's place in the next one.

Fanfiction

I, Eternity, a fanfiction set in The Elder Scrolls universe, follows a mind-bogglingly ancient vampire who was alive (and sometimes an active participant) in long past events from the series history, although he isn't quite as old as canon characters like Vivec.

Film

Eli Damaskinos from the second Blade film. Unlike every other vampire in the series (who look physically middle-aged or younger), Damaskinos actually looks like he's hundreds of years old. Blade III also has Dracula, the very first vampire.
Highlander has Ramirez, a man so old claims that he's forgotten which culture he came from (he's originally Egyptian, posing as a Spaniard and the accent is not even explained in movie, but in the real world, it comes from Not Even Bothering with the Accent.)
- From the same movie is the Kurgan, an immortal villain about a century older than Ramirez. Was roughly three thousand years old at the time of his death.
- In the series, it's implied that however old you are the first time you "die", you're stuck looking that age. Presumably, Ramirez was in his fifties the first time.
In Underworld Evolution, seventy-ish Derek Jacobi plays the original immortal - neither lycan nor vampire but the progenitor of both.
The vampire Akasha in the film adaptation of Queen of the Damned. See the literature section for more information.

Literature

In JRR Tolkien's Middle-earth (The Lord of the Rings, etc) this often happens due to several long-lived and immortal races, from which the respective older ones either survive their peers or simply happen to live a among a different group whose members are younger and less powerful.
- The epitome of this in Lord of the Rings is Tom Bombadil who is called as "The Eldest" by all the races and is described as being ancient by both Gandalf and Treebeard. He even calls himself the First and the Fatherless. This implies he is the oldest living thing (possibly the very first living thing) in Middle-earth.
In The Dark Elf Trilogy, Matron Baenre is said to be at least 2000 years old even though drow are said to have a max life of 800–1000 years - at what ultimately killed her wasn't old age, but an axe to the face.
In The Vampire Chronicles, the eponymous Queen of the Damned is from Ancient Mesopotamia, and was married to the king of the land that would later become Egypt. After becoming a vampire and saving her husband from an assassination by making him one, they became the basis for the myth of Isis and Osiris. She also created other vampires at the time who have survived into the present day.
From the saga of Darren Shan, we have vampires who are mostly been around for a century or two, except for Paris Skyle, a vampire prince about 800 years old at the time of his death, wich is said to be very old for a vampire. At the end of the series, Seba Nile becomes the oldest living vampire, being over 700 years old.
In Succubus Blues, Georgina (the titular succubus) mentions that talking about age among Lesser Immortals is really quite gauche, but she's probably the oldest in her group of friends. Of course, the Higher Immortals are far, far older than that, since they never used to be human. Clues in her life story suggest that Georgina is probably less than two thousand, maybe 1700 or so, from the cusp between Christianity and Grecian paganism.
In the Merry Gentry series, the Fey don't pay much attention to their ages, but Merry continues to discover that her lovers are older and older (than she thought). One of them confirmed he is over 2000 years old, and implied that he might be much, much older than that.
Perry Rhodan does this with Atlan da Gonozal. By the time the 20th-century human protagonists get their first taste of immortality phlebotinum, he's already been stuck on Earth without a way home for ten thousand years. (There are much older characters in the series, of course...but they remain outsiders where Atlan quickly becomes and then stays one of the most important members of the core immortal Nakama.)
In Robert A. Heinlein's works, starting with Time Enough for Love, Lazarus Long is the oldest human being by at least a thousand years. Even in a galaxy of extremely long-lived humans thanks to a combination of the Howard Foundation's applied eugenics program and medical rejuvenation therapy, he's an anomaly, not to mention an artifact, being the only living witness to Old Earth before space travel and the diaspora that seeded humankind among the stars.
There are a few in Steven Brust's Dragaera series. Among the Easterners (i.e. humans), there is the Warlock, who's well past 250. Dragaerans can last around 3,000 years, but the youthful-looking Sorceress in Green has been in the history books for at least 20,000. And then there's Sethra Lavode, who looks Dragaeran but predates the 200,000-year-old empire...
The Dresden Files: Vampires tend to be old, but few are seen older than twice what a wizard usually lives. Injun Joe for reference is about 300. But some of the entities are ancient indeed. The Fairy queens feel like Time Abyss.

Live Action TV

Methos from Highlander the Series is an example. His first memory is about 5000 years ago, and he could be far older than that.
In Forever Knight most vampires we meet are a couple hundred years old at most, but LaCroix was a Roman general who got turned by his preteen stepdaughter during the volcanic eruption at Pompeii.
True Blood has two examples so far. In the second season, Godric is over 2,000 years old, and has tired of vampiric intrigue. In season three, Russell is over 3,000 years old and still bent on domination.
In Buffy the Vampire Slayer and Angel The Master, the Prince of Lies, and Kakistos are all noted as so ancient that they've outgrown human features. The first two Look Like Orlock, while the last has cloven hooves instead of hands. No other vampires seen have shown any sign of happening yet, with the oldest known normal-looking vampire being Darla, at around 400. (Word of God previously stated The Master was about 600 years old, but as he had already stopped looking human when he sired Darla it has presumably been discarded.)
- The Master had inhuman features as much because of his Eviler Than Thou status; he was "impressively" evil even before he became a vampire.
- At one point, The Mayor, who looks middle-aged but is roughly a century old, orders Angel to "respect your elders". Angel mocks him; Angel was turned into a vampire at age 26, but is roughly 240 years old.
In Babylon 5, all the First Ones are immortal, and thus immeasurably old. But Lorien, the guy they all kowtow to, is the first lifeform to achieve sapience in the Milky Way galaxy. He is nothing less than THE First One, and essentially a God for atheists.
In Being Human (UK), few vampires seem to last more than 200 years - Mitchell was just over 100, and he was older than most of the others he met. The Old Ones, however, mostly seem to be around 400-500. Then there's Edgar Wyndham, who casually mentions being "more than a thousand", and Mr Snow, who condescendingly sneers that "These eyes have seen Pharaohs, and the son of a carpenter."

Tabletop Games

In Vampire: The Masquerade and associated media there are some very old vampires around; Napoleonic vampires are seen as relative upstarts by some in the modern age. However, they live in fear of truly ancient vampires and the mythic Antediluvians, the vampires from before Noah's flood, thousands of years ago. And then there's the first vampire, Caine (yeah, that one), who managed to outlive the generation of vampires he directly created who, in turn, created the Antediluvians.
In Warhammer 40,000, you will run across thousand-year-old Eldar relatively frequently. Then you have people like Eldrad Ultharan and Asdrubael Vect, who are old enough to have been around before the Fall.

Video Games

We don't know the exact ages for the non-human characters in Touhou Project, all of whom are Older Than They Look, but the age range among them is from "at least sixty" to "at least 2300, probably a lot more". The oldest character in Gensokyo is usually considered by fans to be either Eirin Yagokoro or Yukari Yakumo.
Some Dragons from Fire Emblem 9~10 can live to 1000 years, while all other laguz' lifespans are far shorter. Lehran tops that at 2000 years, and still looks like a bona fide pretty boy.
In Vampire: The Masquerade Bloodlines, this title belongs to either Beckett or Strauss. Neither state their ages outright, but refer to the 150+ old Prince LaCroix (who was an officer under Napoleon) as "young one".
Magical Girl Lyrical Nanoha A's Portable: The Gears of Destiny reveals that the Materials are older than the already several centuries year old Reinforce and Wolkenritter, with the Book of Darkness having been created to seal them. This lets them know things that even Reinforce doesn't know, such as the fact that the Book of Darkness also contained a secret weapon called the Unbreakable Darkness... which turns out to be an even older and more powerful Humanoid Abomination than the Materials.

Western Animation

In Gargoyles, Hudson is obviously older than the rest of the Gargoyles, and Garoyles have a really long lifespan.
Transformers: We don't even know if there's any kind of upper limit for spark lifespan, but they can survive for millions of years if they take care of themselves. Especially old protagonists tend to be Badass Grandpa / Old Soldier types. We've got Kup from Generation 1, Ratchet (and other Great War veterans) in Animated, and Jetfire from the film series. Jetfire was only showing his age due to lack of energon, but he was still established as much older than the average living Cybertronian.
- And all of the above are practically children compared to Vector Prime, who was literally among the first robots to walk the face of Cybertron, and when asked his age, gives a figure of nine billion.
In Young Justice, Word of God says that Ra's Al Ghul is 600–700 years old. His fellow Light member Vandal Savage, however, is 50,000.
- Both also work with Klarion the Witch-Boy, who, as a Lord of Chaos in this continuity, is presumably pretty old himself, however young he looks.