My thesis considers English literary representations of two notorious classical women, Helen of Troy and Medea, from the twelfth to the seventeenth centuries. My primary focus is on the ways in which male authors in the period deal with the troubling spectres of the women's very different powers: Helen's alarming and captivating sexuality, Medea's magical abilities and unrestrained violence. First tracing how their power is represented in classical and late antique Greek and Latin texts, I then assess how their stories enter the English literary imagination. My project considers both longer renderings of their stories (Gower's Confessio Amantis, Lydgate's Troy Book, Heywood's Ages) and also the brief references to both women that recur time and again in the works of authors including Chaucer, Hoccleve, Gascoigne, Turberville and Greene. My research spans genres and media, considering the various uses the women are put to (didactic, cautionary, tragic, occasionally comic) in history, prose, poetry and drama, as well as in direct translation of classical works. Very often, authors use Helen and/or Medea ironically, in a way that demands a close familiarity with their classical incarnations (particularly, perhaps, with Ovid). Often paired as well as treated separately, Helen and Medea are used across the period to exemplify the unhappy effects of love, the dangerous effects of passion, and perhaps most frequently, the peculiar dangers women pose to men. Though their literary incarnations have often been considered separately by critics, by handling them together my research considers the way authors such as Chaucer, Lydgate, Gascoigne and Turberville choose their classical exemplars very carefully, how two apparently quite different notorious women may be turned to the same ends, used to caution both men and women. Taking their power, and concerted male efforts to undermine it, as its overarching theme, the thesis considers Helen and Medea in relation to medieval and Renaissance theories of translation, to instructional, didactic or cautionary literature, to Christianity, to political and religious upheaval, and most significantly, in relation to the male establishment of the period