Some of the most important saints for the Catholic Church are Mary, St. Joseph, St. Augustine, St. Thomas Aquinas and St. Catherine of Sienna. These saints filled a wide range of roles in Christian history, from that of being the mother of Jesus to being great theologians.
Mary, the mother of Jesus and wife of Joseph, is, according to the Catholic Church, the most important saint of all time. The Catholic Church believes that she was conceived without the stain of original sin, and that she never committed a personal sin throughout her life. The Bible records her close association with her son, even to the point of accompanying him at the cross.
St. Joseph was the husband of Mary and guardian of Jesus on earth. The Bible does say much about him, but many believe he was a man of exceptional holiness. In 1870, Pope Pius IX named St. Joseph as the Patron of the Catholic Church.
St. Augustine and St. Thomas Aquinas were two of the Catholic Church's greatest theologians. St. Augustine developed Christian theology in almost all of its branches, and St. Thomas Aquinas is famous for combining the great insights of Aristotelian philosophy with Christian theology.
St. Catherine of Sienna, a nun of the Dominican Order, had a profound influence over the governance of the Church by convincing the pope to return to Rome during the Great Schism.