A:
Pope John XII was elected at an age, 18 years, when it could hardly be expected that he would remain celibate, especially as many of those around him had mistresses. Russel Chamberlin (The Bad Popes) says that John embarked on a lifestyle that even startled the Romans, accustomed to seeing licentious living, at the same time seeing Rome as a treasury to be plundered. It is said that John XII was beaten to death by a jealous husband coming home to find the pope having sex with his wife.
Pope John Paul I died after slightly more than a month in office.
John Paul II
The pope before John Paul II was John Paul I, who reigned for only 33 days before he died.
Pope John XI died in 936.
Pope John XV died in 996.
Pope John IX died in 900.
John Russell Pope died in 1937.
Pope John XVIII died in 1009-07.
Pope John XIX died in 1032-10.
Pope John Paul II died in 2005.
It is not known how Pope Urban I died. For centuries it was thought that he died a martyr but now it is believed he died of natural causes.
Pope John V died on 686-08-02.