The apocrisiarius or apocrisiary was the legate from the pope to the patriarch of Constantinople, circa 452–743,[1] equivalent to the modern nunciature.
[1] In part, the role of the apocrisiarius was to represent the interests of the Roman church at the imperial court in Constantinople.
[1] According to the Catholic Encyclopedia, "in view of the great importance attaching to the relations between the popes and the imperial court of Constantinople, especially after the fall of the Western Empire (476), and during the great dogmatic controversies in the Greek Church, these papal representatives at Constantinople took on gradually the character of permanent legates and were accounted the most important and responsible among the papal envoys.
[2] The apocrisiarius held "considerable influence as a conduit for both public and covert communications" between pope and Byzantine emperor.
[6] According to the Catholic Encyclopedia, "from the reign of Charlemagne (d. 814) we find apocrisiarii at the court of the Frankish kings, but they are only royal arch-chaplains decorated with the title of the ancient papal envoys.