What would medieval legends be without dragons? According to some versions of Arthurian legend, the dragon Kilgharrah befriended Merlin, King Arthur's protector and resident magi. However, their relationship had its ups and downs. Kilgharrah often offered advice to Merlin (some good, some bad), who sometimes refused to do as the dragon suggested. At one point, Kilgharrah tried to kill Merlin, who in turn vowed he would never help to free her from her enslavement in the castle dungeon. Eventually, Merlin did set the huge, red-hued, bat-winged beast loose. And, in keeping with the dragon's often vengeful attitude, Kilgharrah nearly destroyed Camelot [source: Geoffrey of Monmouth]. If there isn't an ancient platitude about keeping your enemies close and your dragons closer, there should be.