The prōtasēkrētis (Greek: πρωτασηκρῆτις), also found as prōtoasēkrētis (πρωτοασηκρῆτις) and Latinized as protasecretis or protoasecretis, was a senior official in the Byzantine bureaucracy. The title means "first asēkrētis", illustrating his position as the head of the order of the asēkrētis, the senior class of imperial notaries.
The post evolved gradually. The first asēkrētis are attested from the 6th century, and several Ecumenical Patriarchs of Constantinople and one emperor, Anastasios II (r. 713–715), were drawn from their ranks. Aside from possibly anachronistic references to Maximus the Confessor being a prōtasēkrētis under Emperor Heraclius (r. 610–641), the earliest confirmed occurrence (as proto a secreta) comes from the Liber Pontificalis for the year 756. As head of the imperial chancery (the effective successor of the late Roman primicerius notariorum), the position was highly influential: in the 899 Klētorologion of Philotheos, a list of precedence of Byzantine imperial officials, he is placed seventh among the sekretikoi, the financial ministers of the state. From documents and sigillographic evidence, the prōtasēkrētai held the dignities of prōtospatharios, patrikios and anthypatos. Among others, the Patriarch Photios (858–867 and 877–886) held the post.
His subordinates included not only the asēkrētis, but also the inferior class of the imperial notarioi, under their head, the prōtonotarios, as well as the official known as dekanos, placed "in charge of the imperial papers" according to the De Ceremoniis of Emperor Constantine VII Porphyrogenitus (r. 913–959). The prōtasēkrētis seems also to have been in charge of preparing the imperial chrysobulls. After 1106, however, he was moved from the chancery and assumed judicial duties, heading one of the highest courts of the Byzantine Empire, along with the eparchos, the megas droungarios tēs viglas, the dikaiodotēs, the koiaistōr, the epi tōn kriseōn, and the katholikos, who headed the court for fiscal affairs (dēmosiaka pragmata). Although the class of the asēkrētis is not attested after the 12th century, the post of prōtasēkrētis survived into the Palaiologan period.