There is no evidence that the priests of ancient Egypt actually wore masks to portray the many zoomophic gods and goddesses such as Anubis the jackal and protector of the deceased, Horus the hawk protector of the throne,Hathor in her cow headed aspect as the protector of the family and hearth.
This imagery has been created and promoted incorrectly by the makers of motion pictures such as "The Mummy" and "The Scorpion King" purely for effect.