Abraxas

Abraxas or Abrasax is a term for the "Great Archon" in Gnostic Christianity. The word is found in Gnostic texts such as the Holy Book of the Great Invisible Spirit and the Apocalypse of Adam, and also appears in the Greek Magical Papyri. It was engraved on certain antique gemstones, called on that account Abraxas stones, which were used as amulets or charms. (Wikipedia)