Abi Sa'id al-Hasan ibn Yasar al-Basri, often referred to as al-Hasan al-Basri, was an early Medieval Muslim preacher, ascetic, theologian, exegete, scholar, and judge.
Born in Medina in 642 CE, Hasan belonged to the second generation of Muslims, all of whom would subsequently be referred to as the tabi'un in Sunni Islamic piety. He became one of "the most celebrated" of the tabi'un, enjoying an "acclaimed scholarly career and an even more remarkable posthumous legacy in Islamic scholarship."