Servus Servorum Dei is a Latin phrase meaning Servant of the Servants of God. The phrase is one of the titles of the Pope and is used to refer to the Pope in the beginning address of Papal bulls.
Pope St. Gregory I was the first pope to use this title to refer to himself as Pope. The adoption of the title stemmed from a dispute with the Archbishop of Constantinople John the Faster who adopted the title ‘Ecumenical Patriarch’: the humble title ‘Servant of the Servants of God’ countervailed the other’s claim of power and eminence against the Bishop of Rome. Some of Pope Gregory’s successors used the phrase off and on for some centuries, but they did so regularly only from the 9th century. At times, some civil rulers also used this title, but after the 12th century it came to be used exclusively by the Pope.
The Second Vatican Council Popes have used the concept of Servus Servorum Dei to help in making their office a simpler and less regal office. Pope Paul VI stopped using the Papal Tiara, and none of his successors have ever worn the tiara. John Paul I, John Paul II, and Benedict XVI dispensed with a coronation, opting instead for a simpler form of installation. Instead of receiving the Papal Tiara, the three men received the pallium during their installation ceremonies. Also, the royal pronoun ‘we’ was dispensed with in speech and writing, and instead the singular ‘I’ has been used by Paul VI’s successors, except in Latin, a language in which, as in ancient Greek, the more impersonal ‘we’ has the opposite effect to that of the royal ‘we’.