26 April - This is the third pope at the head of the Church from 79 to 91. According to the Liber pontificalis, Clet is of Roman origin. He was born in Patricius in the Equiline region, not far from where St. Peter lived.

Clet led the Church for about 12 years, during the reigns of Vespasian and Titus respectively. According to the rules established by Peter, he ordained 25 priests for the city of Rome, which was subdivided into 25 parishes. The persecution of Christians was still very common and Clet was one of the victims. He died as a martyr in the year 91, and his remains were deposited near St. Peter's in the Vatican on May 6. The Holy See was vacant for 20 days after Clet's death.

One of the highlights of Clet's pontificate was the inauguration of the Colosseum. After the death of St. Peter, Clet transformed his house into a church and he also founded a hospital for the elderly and another for the plague victims; these were the first Christian health institutions. Clet's pontificate brought great enlightenment to the Church of Rome. The churches and hospitals he founded in 79, which were destroyed and then renovated, did not disappear definitively until the 18th century. His successors kept many of his principles, such as the subdivision of Rome into 25 parishes. The use of salvation and the apostolic blessing for the first time is attributed to him. Saint Clet is the patron saint of the city of Ruvo in the principality of Naples.