Elves and dwarves, trolls and giants, talking dragons, valkyries and werewolves: all these are familiar in modern movies and commercial fantasy. But where did the concepts come from? Who invented them? Almost two centuries ago, Jacob Grimm assembled what was known about such creatures in his work on 'Teutonic Mythology', which brought together ancient texts such as Beowulf and the Elder Edda with the material found in Grimm's own famous collection of fairy-tales. This collection of essays now updates Grimm, adding much material not known in his time, and also challenges his monolithic interpretations, pointing out the diversity of cultural traditions as well as the continuity of ancient myth.