The most common names chosen by Popes

In early times, the first Popes would keep theirbaptismal names. But John II, whos birth name wasMercurius, and served as Pope from 533-535, wasthe first to change his name. After him, all men elected Pope have chosen another name to go by during their pontificate.

The most common names used by Popes are: John (23), Gregory (16), Benedict (16), Clement (14), Leo (13), Innocent (12), Pius (12), Stephen (9), Urban (8), Alexander (7), Adrian (6), Paul (6), Sixtus (5), Martin (5), Nicholas (5), Celestine (5), Anastasius (4), and Honorius (4). During his first general audience, which took place at St. Peter's Square, Benedict XVI explained why he chose the name Benedict.  

BENEDICT XVI
Archive April 24, 2005
"I chose the name Benedict XVI because of the legacy of Pope Benedict XV. He was a courageous and authentic prophet of peace, during the chaos of the First World War."

 John Paul I was the first Pope to choose a combined name. He wanted to pay tribute to his two predecessors John XXIII and Paul VI. Up until today, no one has ever chosen the name of the apostle and first Pope, Peter. Not even John XIV or Sergius IV, who shared that baptismal name.