The themes of religion and magic, interwoven in the supernatural, are crucial to the Arthurian legend. Many of its most resonant motifs, both secular and sacred, are linked to the supernatural (quest and adventure, magic and enchantment, prophecy and destiny, miracle and marvel, the search for the Holy Grail), as are some of its most powerful figures (Merlin, Morgan le Fay, the Fisher King). The leitmotif of the supernatural echoes through Arthurian romance from its origins in the twelfth century to its modern manifestations. Writers such as Chrétien de Troyes, the Gawain-poet, Malory, Tennyson, T. H. White and Marion Zimmer Bradley engage in vastly differing ways with the supernatural, but it remains a constant, fundamental to their narratives. While in some contemporary works the supernatural is reduced or floats free of Christianity, the intimate connection between magic, religion and romance, established over something approaching a millennium, is not readily lost. Magic and the supernatural more generally provide romance with its quality of the marvellous, but may also be treated with profundity and realism. Medieval Arthurian legend, the focus of this essay, reflects a Christian world view in which the supernatural is assumed to play a part, and in which religion does not negate the possibility of magic. Some of the central tensions in Arthurian romance, however, arise from the clash between different sorts of supernatural, in particular between the secular (with its origins in the pagan) and the sacred, and the ways that chivalric ideals engage with these.