Alphonsus Maria de Liguori (27 September 1696 – 1 August 1787) was an Italian Catholic bishop and saint, as well as a spiritual writer, composer, musician, artist, poet, lawyer, scholastic philosopher, and theologian. He founded the Congregation of the Most Holy Redeemer, known as the Redemptorists, in November 1732.

In 1762 he was appointed Bishop of Sant'Agata de' Goti. A prolific writer, he published nine editions of his Moral Theology in his lifetime, in addition to other devotional and ascetic works and letters. Among his best known works are The Glories of Mary and The Way of the Cross, the latter still used in parishes during Lenten devotions. He is also associated with the manualist tradition of moral theology and seminary education, which was highly influential in the 19th and early 20th centuries.

He was canonised in 1839 by Pope Gregory XVI and proclaimed a Doctor of the Church by Pope Pius IX in 1871. One of the most widely read Catholic authors, he is the patron saint of confessors.