In the Roman Catholic Church, protonotary apostolic (PA; Latin: protonotarius apostolicus) is the title for a member of the highest non-episcopal college of prelates in the Roman Curia or, outside Rome, an honorary prelate on whom the Pope has conferred this title and its special privileges. An example is Prince Georg of Bavaria (1880-1943), who became in 1926 Protonotary by papal decree.
In late antiquity, there were in Rome seven regional notaries who, on the further development of the papal administration and the accompanying increase of the notaries, remained the supreme palace notaries of the papal chancery (notarii apostolici or protonotarii). In the Middle Ages, the protonotaries were very high papal officials and were often raised directly from this office to the cardinalate. Originally numbering seven, Pope Sixtus V (1585-90) increased their number to twelve. Their importance gradually diminished, and at the time of the French Revolution, the office had almost entirely disappeared. On 8 February 1838, Pope Gregory XVI re-established the college of real protonotaries with seven members called protonotarii de numero participantium, also known as numerary protonotaries, because they shared in the revenues, as officials of the Roman Chancery.
Since the sixteenth century, the popes had also appointed honorary protonotaries, who enjoyed the same privileges as the seven real members of the college; and titular protonotaries, who held a corresponding position in the administration of the episcopal ordinariate or in the collegiate chapter. By the motu proprio Inter multiplices of 21 February 1905, Pope Pius X defined the position of the protonotaries, ... privileges, dress, and insignia of the members of the four classes:
The name of the prothonotary warbler derives from the supposed similarity between its plumage and the golden robes worn by protonotaries.