Was the Titan a Forgotten Beast? I saw one of those at least once per fort. Once it was a completely helpless squirrel made of ears that got caught in a trap without my noticing, once it was a colossal brass spider that casually strolled through my fortress, sticking all my surviving dwarves onto walls and ceilings with a web cannon. I had to wait for those dwarves to die of dehydration, since the fort isn't considered lost while they're still alive, but they couldn't free themselves to eat or drink.