There have been 12 Roman Catholic Popes named Pius:

Honorius has been the name of four Roman Catholic Popes and one Antipope.

Instead, Roman Popes imported Gregorian chant from (German) Holy Roman Emperors during the 10th and 11th centuries.

Later it was owned by the Roman Popes, and was a centre of fightings against the Greek monastic orders.

Pope Leo was the name of thirteen Roman Catholic Popes:

The first recorded use of the title by a Roman Pope was by Theodore I in 620.

A pattern developed wherein Roman Popes imported chant from the German Holy Roman Emperors during the 10th and 11th centuries.

At the Mass, he drew attention to a black-lettered banner that said in Russian: "Moscow wants the Roman Pope."

He was the second Roman Pope of the Western Schism.

Gregory has been the name of sixteen Roman Catholic Popes and two Antipopes.