Medieval people viewed whales in complex and contradictory ways, from marvelous to monstrous to mundane, heaven-sent or hell-bent. Despite this, whales are conspicuous in their absence from most historical and archaeological dialogues on the Middle Ages. Drawing upon a wealth of legal, literary and material evidence, this work details the ways in which whales were sought out and scavenged at sea and shore, fought over in legal and physical battles, and prized for meat, bone and fuel. Using Old Norse sagas, laws and material culture, alongside comparative historical and ethnographic evidence, Monstrous Fishes and the Mead-Dark Sea reexamines the value of whales in the medieval North Atlantic world.