The Catholic Church never formally canonized some of the best-known saints, such as Patrick, Augustine of Hippo and Nicholas of Myra, because the formal canonization process was established in 1234. Saints have been born on every continent but Antarctica. In 2015, the church canonized the first Australia-born saint, Mary MacKillop.
The Catholic Church has often classified saints into the categories of Martyr, Virgin or Doctor, the latter of which is based on contributions to theology or doctrine. The Church also uses the Confessor category for saints who lived faithfully without dying as martyrs.
As of 2015, the Catholic Church recognizes 36 saints as Doctors of the Church, four of whom are female. Teresa of Avila, Catherine of Siena and Therese of Lisieux were three female Doctors of the Church who received the title from Pope Paul VI in 1970. Pope Benedict XVI recognized Hildegard of Bingen, the fourth female Doctor, in 2012. Pope Francis raised some controversy by naming Gregory of Narek as the 36th Doctor of the Church, since this Armenian monastic and mystic was not in full communion with the Catholic Church during his lifetime.
Although the Catholic Church is the institution best known for officially recognizing deceased individuals as saints, veneration of saints and requests for their intercessory prayer to God are also common in Orthodox Christianity. Some Protestant denominations, including the Episcopal Church and the Evangelical Lutheran Church in America, also observe days in honor of particular saints.