Abraxas or Abrasax (Biblical Greek: Ἀβράξας or Ἀβρασάξ) 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.

There are similarities and differences between such figures in reports about Basilides's teaching, ancient Gnostic texts, the larger Greco-Roman magical traditions, and modern magical and esoteric writings.