Medieval manuscripts are often illustrated but miniatures that accompany the text are not the only type of illustration. Images are often inserted as historiated initials or fill the margin of the page as a border decoration. Such marginal images are now studied in terms of both literary history and the history of the book. This essay surveys several examples of such images, especially those of fantastical creatures and hybrid figures known as chimera in the Middle Ages. The possible interaction between the text and such images are discussed with special reference to the Queen Mary’s Psalter and the Luttrell Psalter. It will also be pointed out that in the 15th and early 16th century, as the Book of Hours becomes increasingly popular in both manuscript and print, such images in the margin lose subversive potential and are used frequently as a decorative motif, devoid of the original sense of wonder.