Monstrous iconography was a major, even central, element of the visual arts throughout the entire medieval period, Early Christian through late Gothic, east and west, north and south. There are few—if any—medieval cultural traditions that do not rely on monstrous imagery for vital cultural functions. Within this catchall category, often defined through exclusion from all of the more clearly defined categories of the period, there is tremendous dynamism and variety, as well as great hermeneutic and epistemological potential. There have been a few attempts to define the monstrous, though the protean nature of the subject eludes final clarity.1 However, the study of the iconography of the monstrous was, until relatively recently, underdeveloped. It was a subject of interest within the period, but was not frequently discussed in secondary scholarship about the period. In this essay, we will provide a historiography of modern Monsters Studies, with particular attention to works addressing iconographical concerns, and then will consider the differing cultural and artistic functions of the monstrous.