The Bollandist Society are an association of scholars, philologists, and historians who since the early seventeenth century have studied hagiography and the cult of the saints in Christianity. Their most important publication has been the Acta Sanctorum. They are named after the Flemish Jesuit Jean Bollandus (1596–1665).

A hagiography is a biography of a saint or an ecclesiastical leader, as well as, by extension, an adulatory and idealized biography of a preacher, priest, founder, saint, monk, nun or icon in any of the world's religions. Early Christian hagiographies might consist of a biography or vita, a description of the saint's deeds or miracles, an account of the saint's martyrdom, or be a combination of these.