Alphonsus Liguori, CSsR, sometimes called Alphonsus Maria de Liguori or Saint Alphonsus Liguori, was an Italian Catholic bishop, 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.

The Redemptorists, officially named the Congregation of the Most Holy Redeemer, abbreviated CSsR, is a Catholic clerical religious congregation of pontifical right for men. It was founded by Alphonsus Liguori at Scala, Italy, for the purpose of labouring among the neglected country people around Naples. It is dedicated to missionary work and they minister in more than 100 countries. Members of the congregation are Catholic priests and consecrated religious brothers.