Pope Saint Celestine V reigned a mere five months. The primary objective of his pontificate was to reform clergy. He abdicated on 13 December 1294, the last pope to do so until Pope Benedict XVI.
Pope Saint Pius V (1566-1572) was a Domincan. He called the Council of Trent, Excommunicated Elizabeth I of England for schism, was the patron Palestrina, and organized the Holy League for the defense against the Ottomans at the Battle of Lepanto.
Pope Saint Cletus, the third Pope, governed the Roman Church from about 76 to about 88 during the reigns of the Emperor Vespasian and of Domitian.
We have little definite information about Pope Saint Caius. Iit was said that he was a relative of the Emperor Diocletian and was also an uncle of an unidentified holy Susanna. He also made up the final structure of the lower orders.
Pope Saint Anicetus, the 11th pope, succeeded St. Pius towards the year c. 153, and reigned till about 168. He condemned Montanism, conferred with St. Polycarp on the Paschal date controversy, and forbade priests from growing their hair. He was martyred and is venerated on April 17.
Pope Saint Martin I (649-55) convened a council which condemned the teaching of Monothelism. The Byzantine emperor sent soldiers to kidnap the Pope from the Lateran Basilica. He died shortly thereafter, tortures and cruel treatment having taken their toll. He is the last of the early popes to be venerated as a martyr.
Pope Saint Julius I (337-352) reigned shortly after the Council of Nicaea and was a defender of Orthodoxy against the Arians. He was a supporter and protector of St. Athanasius . His feast day is April 12
Pope Saint Simplicius reigned when the last of the western Roman Emperors fell in 476 a.d.. He defended the action of the Council of Chalcedon against the Eutychian heresy, labored to help the people of Italy against the marauding raids of barbarian invaders. He worked to maintain the authority of Rome in the West.
Pope St. Hilarius (d. 468) had been a trusted aide to Pope Saint Leo the Great. Papal legate. As pope, Hilarius confirmed the work of several general councils, rebuilt and remodeled many churches, fought Nestorianism, and held several Councils at Rome.
Pope Saint Hyginus was bishop of Rome from about 138 to about 140. He was born in Athens, Greece at an unknown date. The Liber Pontificalis also relates that this pope organized the hierarchy and established the order of ecclesiastical precedence (Hic clerum composuit et distribuit gradus). Eusebius claims that Hyginus's pontificate lasted four years.