Beol

King Beol was the king of Geath when the Eleventh Doctor arrived there. He owned a Dragon and was occasionally assisted by the The Teller, who told stories about Beol to the Geathians. (NSA: The King's Dragon) Over time, it would seem the stories had warped his memory of how he had found his "dragon" and he was willing to kill strangers, such as the Doctor, Amy and Rory, who he thought were behind mysterious happenings in his kingdom. However, he was overthrown by the end of the story and replaced with a councillor for the time being.