The Augustinians, named after Saint Augustine of Hippo (354–431), are several Christian monastic orders and men and women living according to a guide to religious life known as the Rule of Saint Augustine.

Prominent Augustinians include the only English Pope Adrian IV Italian Pope Eugene IV, mystic Thomas à Kempis, Dutch Christian humanist Desiderius Erasmus, the German Reformer Martin Luther, the Spanish navigator Andrés de Urdaneta, Italian composer Vittoria Aleotti, German mystic Anne Catherine Emmerich and the Austrian geneticist Gregor Mendel.

The order has made a very significant missionary contribution to Christianity as well as establishing educational and charitable institutions throughout the world.