A chartophylax (Greek: χαρτοφύλαξ, from χάρτα, "document" and φύλαξ, "guard, keeper"), sometimes also referred to as a chartoularios, was an ecclesiastical officer in charge of official documents and records in the Greek Orthodox Church in Byzantine times.
Some monasteries also included a chartophylax or, for the women's convents, a chartophylakissa, in charge of their records.
Codinus calls the Grand Chartophylax the judge of all causes, and the patriarch's right arm.
He adds that this officer was the depository or keeper of all the charters relating to the ecclesiastical rights stored in the chartophylakeion (Archives).
In addition, the chartophylax presided over matrimonial causes, and was the main intermediary between the clergy and the patriarch, controlling his correspondence and access to him.