Nag Hammadi Codices A collection of leather-bound codex manuscripts discovered in 1945 in rural Egypt. The collection includes 52 texts (or tractates); with duplicates taken into consideration, there are 45 unique titles. All of the texts are written in Coptic. There are 12 surviving codices, plus eight unbound leaves titled as the 13th codex. They are held in the Coptic Museum in Cairo.

The Nag Hammadi Codices include many writings that had been lost or unavailable for many centuries. Of the 45 unique titles, 37 were not extant in any form prior to the Nag Hammadi discovery, and three additional ones existed only in unidentified fragments. The net result is that the Nag Hammadi discovery adds to the ancient document collection available to the world 30 relatively complete texts and ten more fragmentary texts, as well as five additional copies of previously known works.

These Nag Hammadi texts bear witness to a range of religious beliefs, many (but not all) of which emerged in the centuries following the advent of Christianity. None of the 45 Nag Hammadi titles were ever included in a canonical list or ancient Christian Bible, and they were never widely authoritative in the early church period; many were even directly named as heretical by early church fathers.