A Doyen is usually the chief of mission that has been accredited for the longest time in a country, and presides over the Diplomatic Corps.

In Italy, as in a number of Catholic countries, this function is entrusted to the Apostolic Nuncio. The Doyen is the spokesman for the Diplomatic Corps in relations with the receiving State, performing chiefly ceremonial duties.

From November 2015 the Doyen of the Diplomatic Corps to the Holy See is H.E. Mr. Armindo FERNANDES DO ESPIRITO SANTO VIEIRA, Ambassador of the Republic of Angola to the Holy See.