The Commentary on the Apocalypse (Commentaria in Apocalypsin) is a Latin commentary on the biblical Book of Revelation written around 776 by the Spanish monk and theologian Beatus of Liébana (c. 730–after 785). The surviving texts differ somewhat, and the work is mainly famous for the spectacular illustrations in a group of illustrated manuscripts, mostly produced on the Iberian Peninsula over the following five centuries. There are 29 surviving illustrated manuscripts (many incomplete or fragments) dating from the 9th to the 13th centuries, as well as other unillustrated and later manuscripts. Significant copies include the Morgan, Saint-Sever, Gerona, Osma, Madrid (Vitr 14-1), and Tábara Beatus codices.
Most unusually for a theological work, the imagery seems to have been included from the start, and is considered to be the work of Beatus himself, although the earliest surviving manuscripts date from about a century after he wrote the book. After about another century, around 950, the size and number of illustrations was expanded. Manuscripts of the work are typically referred to just as a Beatus. They included a Beatus map, a version of the medieval type of world map called the T and O map with added details; this is supposed to have been created by Beatus. It has only survived in some copies.