The Codex Gigas ("Giant Book"; Czech: Obří kniha) is the largest extant medieval illuminated manuscript in the world, at a length of 92 cm (36 in). It is a Romanesque Latin Bible, with other texts, some secular, added in the second half of the book. Very large illuminated bibles were typical of Romanesque monastic book production, but even among these, the page-size of the Codex Gigas is exceptional. The manuscript is also known as the Devil's Bible due to its highly unusual full-page portrait of Satan, the Devil, and the legend surrounding the book's creation. Apart from the famous page with an image of the Devil, the book is not very heavily illustrated with figurative miniatures, compared to other grand contemporary Bibles.

The manuscript was created in the early 13th century in the Benedictine monastery of Podlažice in Chrast, Bohemia, now a region in the modern-day Czech Republic. The manuscript contains the complete Latin Bible in the Vulgate version, as well as other popular works, all written in Latin. Between the Old and New Testaments is a selection of other popular medieval reference works: Flavius Josephus's Antiquities of the Jews and The Jewish War, Isidore of Seville's encyclopedia Etymologiae, the chronicle of Cosmas of Prague (Chronica Boemorum), and medical works: an early version of the Ars medicinae compilation of treatises, and two books by Constantine the African.

Eventually finding its way to the imperial library of Rudolf II, Holy Roman Emperor in Prague, the entire collection was taken as spoils of war by the Swedish Empire in 1648 during the Thirty Years' War, and the manuscript is now preserved at the National Library of Sweden in Stockholm, where it is on display for the general public.