Cardinal Joseph Ratzinger has chosen for his name as pope "Benedict XVI." Exactly how many previous "official" Popes Benedict there have been is a little fuzzy, for one of the officially-numbered Benedicts (Benedict X) was definitely an antipope, and one (Benedict V) may be considered an antipope. Most of the popes named Benedict reigned in the Middle Ages.
Following is a quick rundown of all the popes and antipopes named Benedict through the centuries, beginning with the undisputedly official popes of the Middle Ages (antipopes and possible antipopes are on the next page).
Benedict I - 575-579
Thanks to the invasion of Italy by the Lombards, the first Benedict had to wait nearly a year for his election to be confirmed by the emperor in Constantinople. Little is known about him except that he died in the midst of the famine that accompanied the ravages of the barbarian invaders.
Benedict II - 684-685
The second Benedict, who was made a saint, was known for his singing. It took nearly a year for his election to be ratified, and the delay inspired him to get Emperor Constantine Pogonatus to sign a decree ending the requirement for confirmation by an emperor -- but the elections of future popes were still confirmed by emperors for some time.
Benedict III - 855-858
There was some trouble with the third Benedict's election. The legates that were sent to Emperor Louis II the Bavarian for imperial confirmation were persuaded -- or coerced -- to throw their support behind Anastasius the Librarian, whom the emperor confirmed as pope. Benedict was thrown in jail, but in time his supporters won the day and his election was ratified. Benedict III may have met the future Alfred the Great when the prince visited Rome with his father, King Ethelwulf.
Benedict IV - 900-903
We know next to nothing about this Benedict, except that he excommunicated Baldwin II of Flanders for having Archbishop Fulk of Reims assassinated.
Benedict VI - 973-974
The pontificate of Benedict VI was unremarkable but for its tragic end, when he was imprisoned by a faction of the Roman nobility headed by Crescentius and, after two months, reportedly strangled.
Benedict VII - 974-983
The Roman faction that had killed Benedict VI had put the antipope Boniface VII on the throne, but Emperor Otto II sent his representative Count Sicco to handle matters. Sicco expelled Boniface and saw to it that an election was held, whereupon Benedict VII was chosen pope.
Benedict VIII - 1012-1024
Benedict IX - 1032-1044, 1045, 1047-1048
The last of the popes from the Tusculani family, Benedict IX was imposed on the chair at about age 20 by his father Alberic. His violence and debauchery provoked the Romans to revolt, and he fled for his life. Another pope, Sylvester III, was elected; but Benedict's brothers drove Sylvester out in 1045. Benedict did not remain pope long this time; possibly because he wanted to marry, he sold the papacy to his godfather, a priest, who became Gregory VI.
But then Benedict changed his mind and returned to Rome claiming to be the true pope, at the same time that Sylvester also returned to Rome, also claiming to be the rightful pope. Henry III of Germany stepped in and deposed all three popes, putting Clement II on the papal chair. After Clement's death, Benedict returned one last time and installed himself as pope in November of 1047. He lasted 8 months before he was driven out by order of Henry. He was never seen in Rome again, and is believed to have become a penitent at Grottaferrata until his death in 1055 or 1056.
Benedict XI - 1303-1304
Elected unanimously in October, this Benedict lived only until the following July. Most of his papacy dealt with the aftermath of his predecessor's unlawful arrest by Philip IV of France. He was beatified in the 18th century.
Benedict XII - 1334-1342
The third pope to reside at Avignon, where he built an expensive papal palace, Benedict XII was in the papal chair when the Hundred Years' War began. He attempted to reform the religious orders, but his strict rules were met with hostility, and his reforms were undone by later popes.