My first serious DND character was an old elf - 300 years old in fact. Yet he was level 1, despite the world having been almost covered in undead for most of that time.
The DM and I worked it out, though. There were already isolated pockets of life in the world, holding back the undead in various ways. The city we started it used martial force and paladin magic. An enclave of monks hid in an antimagic field. The elves and feyfolk, it turned out, resided on a remote volcanic island in tune with the 4 elements. It wasn't magically hidden, just so remote that the three lichlords didn't even know. They barely cared about any survivors actually, more interested in their bizarre personal research/goals and keeping wary eyes on each other.
But anyway, my character was a diplomat to the fey from the elves. It basically involved playing games and being pranked for 250 years. Sounds sorta horrific, actually, but apparently he came away with a fanatic belief in the innate goodness of all creatures. And like, no actual worldly knowledge. Just a Vow of Poverty and a high diplomacy skill from his painful naivety.
Getting sent to check on the paladin city and its constant war for survival was a pretty rude awakening, heh. And we almost had a party fight when our fighter murdered some captured Asmodeus cultists.
Turned out surprisingly well, though. Around level 12, I think, we had a climactic battle with a demon we'd unleashed. Our CN fighter sacrificed himself to seal it in Limbo, our LE bard (I know, multiclassed) left to study the Book of Vile Darkness, and my Exalted NG druid gave up his Exalted status as naive. But remained NG, and became governor and protector of his home (the Everfree Isles), enlisting the aid of several unsavory sorts to help protect that very naivety.
After all, it's kinda his fault that the Lichlords learned of the Isles. But a rocky alliance with a Machiavellian vampire... well, that's a long story, which we mostly experienced third-hand as a new party.
He did have to say goodbye to Duskwing, his celestial owl companion. But she's waiting for him in Elysium.
I *love* retiring characters.
(His son, my next PC was a Satyr and had no mother, and eventually became an alienist heehee)