Hagiography ( /ˌhæɡiˈɒɡrəfi/) is the study of saints.

From the Greek (h)ağios (ἅγιος, "holy" or "saint") and graphēin (γράφειν, "to write"), it refers literally to writings on the subject of such holy people, and specifically to the biographies of saints and ecclesiastical leaders. The term hagiology, the study of hagiography, is also current in English, though less common. This latter term, in fact, follows original Greek practice, where ἁγιογραφία refers to visual images of the saints, while their written lives (βίοι or vitæ) or the study thereof are known as ἁγιολογία.

Christian hagiographies focus on the lives, and notably the miracles of men and women canonized by the Roman Catholic church, the Anglican Communion, the Eastern Orthodox Church, the Oriental Orthodox Church, and the Church of the East. Other religions such as Buddhism and Islam also create and maintain hagiographical texts concerning saints and other individuals believed to be imbued with the sacred.

The term "hagiographic" has also been used as a pejorative reference to the works of biographers and historians perceived to be uncritical or "reverential" to their subject. Nonetheless, hagiographic works, particularly those of the Middle Ages, can often incorporate a valuable record of institutional and local history, and evidence of popular cults, customs and traditions.