Commentary on the Apocalypse is a book written in the eighth century by the Spanish monk and theologian Beatus of Liébana (730–785) and copied and illustrated in manuscript in works called "Beati" during the 10th and 11th centuries AD. It is a commentary on the New Testament Apocalypse of John or Book of Revelation. It also refers to any manuscript copy of this work, especially any of the 27 illuminated copies that have survived. It is often referred to simply as the Beatus. The historical significance of the Commentary is made even more pronounced since it included a world map, which offers a rare insight into the geographical understanding of the post-Roman world. Well-known copies include the Morgan, the Saint-Sever, the Gerona, the Osma and the Madrid Beatus codices.

The Morgan Beatus is an illuminated manuscript with miniatures by the artist Magius of the Commentary on the Book of the Apocalypse by the eighth-century Spanish monk Beatus, which described the end of days and the Last Judgment. The manuscript is believed to have been produced in and around the scriptorium of the Monastery of San Miguel de Escalada in Spain. Having been created at some time in the 10th century, the Morgan Beatus is one of the oldest examples of a revived Spanish apocalypse tradition. According to the style it was created by Mozarabs. As one of the earliest works of Mozarabic art, the Morgan Beatus exemplifies the interworking connections between the Christian citizens of Spain under the Muslim Moorish leaders, especially in newly Arabicized areas such as Léon and Córdoba. The Apocalypse and the commentary on this scripture by Saint Beatus of Liébana became one of the most important religious texts of the Middle Ages, and was often illustrated very fully.