A regnal name

[CyrilSebastian]

               A papal name is a regnal taken by popes.     
               Pope Adrian VI kept his baptismal name of Adrian VI.     
               The last pope to use his baptismal name was Pope Marcellus II in 1555.       
               He was born Marcello Cervini.             
               
               

[CyrilSebastian]

Pope John XXIII was Pope from 1958 to 1963.   
Faced with selecting a name, Cardinal Roncalli (John XXIII) seriously considered "Joseph".   
He demurred only because no Pope had ever had the name of Joseph before.

[CyrilSebastian]

Pope Julius II was ruler of the Papal States from 1503 to 1513.   
He chose his papal namer not in honor of Pope Julius I but in emulation of Julius Caesar.

[CyrilSebastian]

Pope John II, born Mercurius, was Bishop of Rome from 533 to 535.   
He was the first pope to adopt a new name upon elevation to the papacy.