Pius V
Pope from 1566 until his death (1504–1572), born Antonio Ghislieri in Bosco, near Alessandria, a Dominican friar and inquisitor before his election as pope, and the pontiff who applied with implacable rigour the reforms decreed by the Council of Trent (1545-1563), definitively consolidating the Catholic response to the Protestant Reformation known as the Counter-Reformation. His personal life, of a monastic austerity he maintained even after becoming pope — he often walked barefoot in procession and wore the Dominican habit beneath his vestments — set an example for the moral reform of the Church he himself harshly demanded of the clergy, fighting nepotism, simony and the relaxation of ecclesiastical customs with an energy that earned him both admiration and fear. He promulgated the Roman Catechism (1566), the first unified official catechism for the entire Catholic Church, designed so that priests could instruct the people uniformly and correctly according to Tridentine doctrine; and he imposed the Tridentine Mass through the bull Quo primum (1570), establishing a single, obligatory liturgical rite throughout the West that would remain essentially unchanged until the liturgical reform of the Second Vatican Council four centuries later. He excommunicated Queen Elizabeth I of England in 1570, aggravating tensions between Catholics and Protestants in the British Isles, and organised the Holy League that decisively defeated the Ottoman fleet at the Battle of Lepanto (1571), a victory he attributed to the intercession of Our Lady of the Rosary and commemorated by instituting the corresponding liturgical feast. Canonised in 1712, he is venerated as one of the great architects of modern post-Tridentine Catholic identity.