It would only be short if the pope either died or resigned early in his reign. A pope is elected for life and some popes have been in office for over 30 years.
Pope Gregory IV ruled from 827 to January 844.
Pope Stephen IV followed the reign of Leo III.
During his reign as pope he visited 129 countries.
Pope Francis has not been succeeded at the time of this answer.
There were three popes during Queen Victoria's reign (1837-1901): Pope Gregory XVI (1831-1846) Pope Pius IX (1846-1878) Pope Leo XIII (1878-1903)
Pope John XXIII called the council and Pope Paul VI continued it in his reign.
Pope John Paul I reigned only 33 days.
He reigned from 1963 to 1978.
The Short Reign of Pippin IV was created in 1957.
The Short Reign of Pippin IV has 188 pages.
Innocent was pope number 40. His reign started December 22, 401, and ended on March 12, 417.
A pope is elected for life or until he decides to resign. His reign ends upon his death.