Before there was anything, according to Egyptian mythology, there was an endless expanse of water. What name was given to these primordial waters and the being who personified them?

The name given to these primordial waters and the being who personified them was Nun.

Explanation:

In Egyptian creational myths, Nun or Nu is the oldest of the gods. He is the embodiment of the waters of chaos, the primeval waters. Nun is the father of Ra, the sun god, who rose from the primeval waters on a hillock and created himself and other gods. In Ancient Egypt, it was believed that Nun was the one who caused the annual flood of the Nile. It was also believed that the primeval waters never ceased to exist and that, each morning, as the Sun rose from the waters, the creation of the ordered cosmos was being reenacted.