Fantasy heroes endure. They are embedded in our cultural fabric, dwarfing other literary figures and the mere men and women of history. Achilles and Odysseus, Gilgamesh and Beowulf. King Arthur and Robin Hood, Macbeth and Sherlock Holmes, Conan and Luke Skywalker. They dominate our legends, and tower over popular culture. The stories we tell each other begin and end with fantasy heroes, and the 21st Century is as thoroughly captivated with them as ever. From Batman to Gandalf, Harry Potter to Tyrion Lannister, the heroes of fantasy speak to-and for-whole generations. But what makes a fantasy...