Rosemary Jackson's Fantasy: The Literature of Subversion asserts that "the fantastic in literature revolve[s] around this problem of making visible the un-seen, of articulating the un-said." The fantastic is "preoccupied with limits, with limiting categories, and with their projected dissolution." She explains that fantasy and science fiction also "subvert[s] dominant philosophical assumptions which uphold as 'reality' a coherent, single-viewed entity." Though the current trend in young adult fantasy and science fiction marketed to young adult women supports the hegemonic culture, there are a number of authors subverting the presence of that "single-viewed entity." This thesis explores the manner in which these authors have created heroines that honor and celebrate the realities of their readership versus supporting "dominant philosophical assumptions." It will examine how their heroines reflect various ethnicities, body types, and sexualities, creating a space for the "un-seen" and articulating the "un-said." Ultimately, the works created by these authors provide a valuable critique of current cultural standards and a validation of young adult fantasy and science fiction that promotes diversity. Of course, these works are subject to the constraints of commodification and the genre's sometimes less than positive image in academia. Despite the criticism, the existence and propagation of these texts is essential, especially given the dissolution of the limiting publishing environment in which these works are attempting to survive.