Augustine of Hippo (Latin: Aurelius Augustinus Hipponensis; November 13, 354 – August 28, 430), also known as Augustine, St. Augustine, St. Austin, St. Augoustinos, Blessed Augustine, or St. Augustine the Blessed, is Bishop of Hippo Regius (present-day Annaba, Algeria).

He is a Latin philosopher and theologian from Roman Africa.

His writings are very influential in the development of Western Christianity.

According to his contemporary, Jerome, Augustine "established anew the ancient Faith."

In his early years he is heavily influenced by Manichaeism and afterward by the Neo-Platonism of Plotinus.

After his conversion to Christianity and baptism in 387, Augustine develops his own approach to philosophy and theology, accommodating a variety of methods and different perspectives.

He believes that the grace of Christ is indispensable to human freedom, and he frames the concepts of original sin and just war.

When the Western Roman Empire is starting to disintegrate, Augustine develops the concept of the Catholic Church as a spiritual City of God (in a book of the same name), distinct from the material Earthly City.

His thoughts profoundly influences the medieval worldview.

Augustine's City of God is closely identified with the Church, the community that worships God.

In the Catholic Church and the Anglican Communion, he is a saint and pre-eminent Doctor of the Church, and the patron of the Augustinian religious order; his memorial is celebrated 28 August, the day of his death.

He is the patron saint of brewers, printers, theologians, the alleviation of sore eyes, and a number of cities and dioceses.

Many Protestants, especially Calvinists, consider him to be one of the theological fathers of Reformation due to his teaching on salvation and divine grace.

In the Eastern Orthodox Church he is considered Blessed, a title meaning that the Church has officially recognized that Augustine is most likely in heaven.

This is a step in the Eastern Orthodox process of canonization.

His feast day is celebrated on 15 June.

Among the Orthodox, he is called "Blessed Augustine", or "St. Augustine the Blessed".