The Black Death, estimated to have killed up to one-third of Europeans from 1347-1351, caused changes in society that we cannot imagine. Some of those changes wind up on record, however. Consider, for instance, important positions in government or the church.
The first Archbishop of Canterbury was St. Augustine* (died c.604), who was sent by Pope Gregory I to bring Christianity to Kent in 597. The office is even referred to sometimes as "The Chair of Augustine." Gregory's proposed methods for missions was discussed here. The position became the most important Christian post in England, and candidates for it—chosen by election from their peers or appointed by the king (which led to many conflicts over the years)—had to travel to be confirmed personally by the Pope.
During the plague years, maintaining the office was difficult. John de Stratford, who became Archbishop in 1333, died of the plague in 1348. The election for his successor created a conflict: the canons voted for Thomas Bradwardine, while Edward III wanted them to choose his Chancellor, John de Ufford. The king's choice was grudgingly accepted, de Ufford was declared by the pope to be the new Archbishop, but he died before he could be consecrated back in Canterbury. So Thomas Bradwardine got his chance after all. Bradwardine made the trip to Avignon to be confirmed by Pope Clement VI, but died in Rochester of the plague on his way back to London. He had officially been Archbishop for only 40 days. Fortunately, the next candidate, Simon Islip—the fourth archbishop in 16 months—was confirmed in December of 1349 and lasted for 17 years.
Islip had his work cut out for him, however. As Archbishop following the plague, he was faced with the problem of too few priests in the country. Priests were demanding greater stipends for their work, to which the normally frugal Islip objected both personally and professionally. He worked to regulate their fees, and increased the pace of finding more priests to fill parishes and other posts. Despite his efforts, many in the years to follow would comment on the unhappy change in the post-plague quality of priests, claiming that quantity prevailed over quality in the selection of new clergy.
Although the plague returned at regular intervals, its effects were never as radical as the first time through the population. Islip survived these further outbreaks, but suffered from a stroke in 1363; he spent the last three years of his Archbishopric debilitated while subordinates kept things running. Before he became ill, he did manage to resolve a long-standing dispute between the positions of Archbishop of Canterbury and Archbishop of York, but that's a tale for another day.
*Note: Not the same as the earlier Augustine of Hippo.