Medieval Arthurian stories typically feature noble knights as their main characters, and follow these knights on various quests as they work to fulfill their destiny. Although women do not get to appear as the central characters in these stories, they are oftentimes afforded magical abilities that provide them with a great deal of power and influence. This thesis investigates the role of magical women, including fairies and sorceresses, in medieval Arthurian literature. I explore the conditions under which medieval authors permitted women characters to have power, magical or otherwise; for each of five different magical women appearing in Arthurian stories written between the 12th and 15th centuries, I discuss their different abilities, motivations, and major actions. Even when these fairies are fairly powerful and autonomous in their choices, their motivations are typically related to the interests of the male man character. Their relationship to the heroes of their respective stories determines their characterization. I argue that there are three major tropes that these characters fulfill: fairy caretakers, fairy lovers, or evil sorceresses.