St Clement (c96 AD) was St Peter's successor as Bishop of Rome. His only surviving writing, a letter to the community at Corinth (which deals with a dispute over priests that had been removed from office for assorted offences) is important evidence for the primacy of the Bishop of Rome in the early Church. It also provides an early assertion for the authority of priests in relation to the laity, a useful counter to 'congregationalism' (while also demonstrating that there are no new heresies, no new disputes in the Church; only old ones reborn...).
Reading 3 of Matins on the saint:
Clement, a Roman and disciple of blessed Peter, assigned each of the seven districts of the City to a notary who was to investigate carefully the sufferings of the Martyrs and their deeds and to write them down. He himself wrote a great deal to explain the Christian religion rightly for the salvation of others, Because he was converting many to the faith of Christ by his teaching, and the holiness of his life, he was exiled by the emperor Trajan to the wilderness near the city of Cherson across the Black Sea. There, he found two thousand Christians who had been similarly condemned by the emperor. When he had converted many nonbelievers in that region to the faith of Christ, at the command of the same emperor he was cast into the sea with an anchor tied to his neck, and won the crown of martyrdom. His body was later brought to Rome by Pope Nicholas I and honorably buried in the Church which had already been dedicated to him.
St Felicitas of Rome (c. 101 - 165) is an early martyr who was buried in the Cemetery of Maximus, on the Via Salaria on a 23 November. She was the mother of the seven martyrs whose feast is celebrated on 10 July.