Spoiler ahead. I guess nobody cares anyway, but I did warn you.
I'm pretty sure I had ~3 worlds with a "waxy federation"... seems to be an self-evident name.
Anyway best ending... I cleansed a smaller world once with a hero-tier swordswoman, where I had set the numbers of demons, civilisations, night creatures and megabeasts to ridicolous heights. Letting nothing live that I was given a quest for. (I save-scummed four times, I think. Yes, I'm a horrible person.) Anyway, after that she was obiously legendary in just about everyting, attributes probably maxed out, bla bla bla, but the most interesting thing was a peasant I had picked up halfway through my rampage.
He had >40 kills(I might be wrong... I don't have the scrrencaps on this computer. It was probably much more.) half of which humanoids, other half nightcreatures.
I think in this version knives were even more powerful or something... anyway, his specialty was cutting of lower bodies of his enemies. I nicknamed him the disemboweler, essentially. He was impossible to kill. He could maim everything. He was strong enough to cleave a night crature in two. And the only memorable things in his description was basically that he was fat, and had scars on places where people shouldn't survive being cut.
In every other game(than df) I would probably have been slightly annoyed by this stereotypical invincible farmer-to-warrior guy, except: he was awesome. He got spammed by Giant Eagles. survived. Dodged into a river...survived. Dusted by a forgotten beast in a cave, survives while most party members suffocate and my swordswoman throws rocks.
This was a version long before vampires, I should probably note.
Anyway, after everything evuhl was dead, my adventurer had her ridicolous amounts of kills and the world saw a Golden Age, I retired her and her battered crew, and forgot about this.
Then, months later, i found the safe, and I decided to craft an ending to this story.
I made a fortress, and dug a staircase to Hell. The Golden Age ended the moment my miner broke through the adamantium, I think.
I abandoned it after a short slaughter and reactivated my adventurer, looked for the disemboweler and we set out.
Just us two, because there was no one else who could do it. My adventurer in the best equipment a human can gather, bronze and iron, with a sword of steel an a shield of copper, and the old peasant, in his rags and with a boning knife in every hand(I don't know how THAT happened).
We travelled to the ruin, just a short walk to the north. No one saw us, and no one stopped us, and the evening came,as we pushed open the Doors of Doomgate.(a cheesy name, I admit.but it was the one thing the fortress was build for.)
I dispatched the first demons with ease, and we pushed forward into the deep. the devils flocked around us, and we grinded to a stop on the staircase. The peasant started killing, I started dying:
first a slashed arm, then a chipped leg-bone. I don't know about the newest versions, but in this one that was a death sentence. I slowed down to ~20% of my normal speed and then gave in to the pain as soon as I took some other hits. In the meanwhile, the disemboweler hadn't even got hurt. A giant gecko, twisted into human form by Hell itself finally took mercy on me and ended my story with a devastating punch to the head.
I could exit the game and leave this world how it was: finished. The peasant would stand on this staircase, mute, incredible small above the hulking demons, and cut them until they died, for as long he needed to; for as long as hell could spare warriors. The world, at last, was save.
tl,dr: Peasant was op