St. Alphonsus Liguori (1696–1787) was an Italian bishop, theologian, and founder of the Congregation of the Most Holy Redeemer (the Redemptorists). Born in Naples, he excelled in law before turning to the priesthood at the age of 30. He dedicated his life to preaching and teaching, focusing on the poor and marginalized. 

St. Alphonsus is renowned for his prolific writings, particularly in moral theology, which emphasized God's mercy and love. His most notable works include "The Glories of Mary" and "Moral Theology," which are still influential in Catholic education. Canonized in 1839, he was declared a Doctor of the Church in 1871 for his significant contributions to theology. His feast day is celebrated on August 1, and he is the patron saint of confessors and moralists, known for his compassionate approach to pastoral care.