Why were the Anglo-Saxons obsessed with monsters, many of which did not exist? Drawing on literature and art, theology and a wealth of first-hand evidence, Basilisks and Beowulf reveals a people huddled at the edge of the known map, using the fantastic and the grotesque as a way of understanding the world around them and apprehending something of a divine plan. It is for these reasons that monsters were at the very centre of their worldview. From map monsters to demons, dragons to Leviathan, we neglect them at our peril.