In contrast to the Igigi, the Babylonian (Sumerian/Akkadian) spirits of the heavens, the Anunaki (Annunki, Annunnaku, Annunna) were the spirits of the Earth. According to legends, they were created by Anshar and Kishar (or Marduk) and are symbolized by the stars of the northern sky. They were originally chthonic fertility deities, later evolving into seven judges of the underworld who answered only to Kur and Ereskigal.
Modern archeology and mysticism are rewriting the place of such entities as the Anunki and Igigi. To read more, check out these sites:
What About the Anunnaki?
The Legends of the Garden of Eden and The Angels
Origins of the devil...
The Mesopotamian Texts