Imaginary beasts have figured prominently in literary works ever since the ancient world, when these myths were first formulated. But the nineteenth century witnessed the rise of science, the discovery of geological findings that challenged the biblical myth of creation, and the birth of Darwin's theory of evolution. Since then, monsters have evolved from supernatural creatures to natural ones endowed with exceptional size, strength, or intelligence. This book explores both literary and cinematic texts that are especially explicit in their Darwinian portrayal of monstrous beasts, though these creatures retain an archaic mythological quality. The myth of Leviathan and Behemoth, for instance, is as central to "Jaws" as it is to "Moby-Dick;" indeed, "Jaws" inherits the myth directly from "Moby-Dick, " as does "King Kong." These and other monster tales, such as "The Creature from the Black Lagoon" and "Grendel, " keep the ancient myth alive and relevant by recasting it in the context of biological and cultural evolution. There is a pattern of alternating bestialization and anthropomorphism in many monster tales, suggesting that these images are being displayed in repeated attempts to define who we are in relation to animals. Thus the more beastly the monster, the more insistently we erect the old paradigm of the Ladder of Being, placing ourselves on a higher and separate rung; but the more human-like the creature, the more readily we shift to the paradigm of the Tree of Life, in which all creatures are more closely related. Since the matter of distinctions between species also involves questions of race, the monster myth is often conscripted to serve racist agendas. But more often than not, the myth has an anti-racist subtext that undercuts the hierarchy. The closing chapters of the volume consider the notion of artificial evolution in works such as "The Island of Dr. Moreau, " and human-machine interaction in "Gravity's Rainbow." As fables of identity, monster tales dramatize our anxieties and fears about our own animal nature and provide a means of coming to terms with our evolution.