The fortress of joyoushammer was in it's second summer when disaster struck. The forgotten beast Xan Buryraunches arrived! (a towering thornbill with forked antennae, green feathers, and a poisonous bite). The fortress was just over a year old, so this was not a good thing. I had an untrained military with no armor (I had only recently produced a few silver warhammers and bronze swords)
It effortlessly plowed through the undead draltha herds in the caverns, so I knew I was in trouble. My military confronted the creature at the entrance to my fortress. My dwarves fought bravely, but both my main squads were defeated and only some dabbling wrestlers from a third squad remained, half the population was already lost. Xan buryraunches the abbyses of mold stormed up the stairs into the main fortress. I gave up all hope, but decided to at least check out that artifact throne I had just gotten a message about before ending the game. It was nothing special.
I went back to the forgotten beast and found out that it was....DEAD!! I checked the three surviving members of my military (two of them were badly wounded) to see who had saved my fortress, and found they had no kills. Since I felt the urge to reward the unknown hero with gifts and a legendary dining room, I looked at my other dwarves and found the hero was the most unlikely suspect. Onúl clapfountains, the legendary baby meatshield.
Her mother had given birth to her while in combat with Xan, the first thing poor Onúl saw in this world was Xan tearing apart and killing her father. Not much later Xan learned that you should never piss off a dwarven baby.
Here's the combat log for our young hero: