The ambassadors of the Vatican to other countries are usually called nuncios.

The six highest ranks of diplomatic representatives of the Vatican are:

legatus a latere

nuncio with full powers of a legatus a latere

legate

nuncio of the first class

nuncio of the second class

internuncio

A papal legate is the personal representative of the Pope who carries his authority. There are three kinds of papal legates: Legates a latere, nuncios (A diplomatic agent of the pope with rank equal to that of an ambassador), and legati nati. A legates a latere is a legate for an important mission of the Holy See, which is temporary. Legatus Natus were holders of certain offices that carried the same legal status as a papal nuncio. (not be confused with an apostolic prefect or apostolic vicar, who is sent with special sacramental faculties to administrate and serve an evangelical mission) Before the protestant revolt, the Archbishop of Canterbury was a legatus natus.

Conus legatus was created in 1810.

Legation.

"Legatus" is a Latin word that means "envoy" or "ambassador." In ancient Rome, a legatus was a high-ranking military officer appointed by the emperor to command a legion or lead a diplomatic mission.