The Byzantine Iconoclasm were two periods in the history of the Byzantine Empire when the use of religious images or icons was opposed by religious and imperial authorities within the Ecumenical Patriarchate and the temporal imperial hierarchy. The First Iconoclasm, as it is sometimes called, occurred between about 726 and 787, while the Second Iconoclasm occurred between 814 and 842. According to the traditional view, Byzantine Iconoclasm was started by a ban on religious images promulgated by the Byzantine Emperor Leo III the Isaurian, and continued under his successors. It was accompanied by widespread destruction of religious images and persecution of supporters of the veneration of images. The Papacy remained firmly in support of the use of religious images throughout the period, and the whole episode widened the growing divergence between the Byzantine and Carolingian traditions in what was still a unified European Church, as well as facilitating the reduction or removal of Byzantine political control over parts of the Italian Peninsula.

An icon is a religious work of art, most commonly a painting, in the cultures of the Eastern Orthodox, Oriental Orthodox, and Catholic churches. They are not simply artworks; "an icon is a sacred image used in religious devotion". The most common subjects include Jesus, Mary, saints, and angels. Although especially associated with portrait-style images concentrating on one or two main figures, the term also covers most of the religious images in a variety of artistic media produced by Eastern Christianity, including narrative scenes, usually from the Bible or the lives of saints.