The Ennead were the nine great Osirian gods: Atum, Shu, Tefnut, Geb, Nut, Osiris, Isis, Set, and Nephthys. The term is also used to describe the great council of the gods as well as a collective term for all the gods.
Atum was the first who created himself (or arose out of Nu, the primal nothingness) and who created Shu and Tefnut from either his spittle or his blood. From their union came Geb and Nut. Their children, the great-grandchildren of Atum, were the first gods of earth: Osiris and Isis, and Set and Nephthys. From those four were all the pharaohs and many of the gods descended.