Builders

The Builders were the creators of Ember. Roughly 250 years before Book 1: The City of Ember, they created the titular city of Ember, and went out of their way to ensure that all knowledge of them other than their existence as the city's creators would be erased. They also left behind The Instructions to be passed down from one Mayor of Ember to the next.

In actuality, Ember is an underground city created by the Builders to serve as a shelter from the fallout of numerous World Wars and pandemics on a nigh-apocalyptic scale. They saw fit to erase all knowledge of not only themselves, but the world that came before, to ensure the people of Ember would be able to emerge and start civilization anew without being influenced by knowledge that might drive them to repeat the mistakes of their forbearers.