This thesis argues that the view of human nature which emerges from Shakespeare's plays is essentially hybrid, protean and metamorphic. Chapter I discusses various early modern theories of the self and subsequent chapters explore the transforming power of love, twins and other doubles, transvestite heroines, the relationship between actor and role and the various forms of the monstrous in The Tempest. The plays considered include early, middle and late works and examples of comedy, tragedy, history and romance.