This dissertation examines representations of monstrosity and physical deformity in Italian Renaissance texts and how such images opposed an Idealism advocated by Neoplatonism. The texts examined concentrate specifically on three aspects: disease, gender, and the supernatural, all of which affect the body in ways considered ugly and repulsive. Renaissance Idealism found its greatest expression in treatises that placed emphasis on beauty; however, there existed a divergent yet equally important vein in this period that was fascinated with pervasive images of a monstrous, ugly and altered body, and its function in the social and political context of society. Chapter One examines syphilis in Girolamo Fracastoro’s Syphilidis sive de Morbi Gallici. Influenced by a renewed interest in Ovid’s Metamorphoses, Fracastoro uses myths to explain the disease’s origins and to develop his own theories about contagion. While portraying the ugliness of syphilis through poetry, Fracastoro’s main goal is to show that sexual intercourse is the catalyst for the gruesome physical transformations that affect the body. Chapter Two considers monstrosity and ugliness in regards to gender and the female figure. By analyzing the works of Giovan Battista Verini, Pietro Aretino and the misogynistic poetry of Lorenzo and Maffio Venier among others, I argue that male authors targeted women, specifically courtesans and prostitutes, as sources of disease and ugliness as a reproach for female encroachment on traditionally male social and literary circles. I also trace the use of the Danae myth and its evolving portrayal of the female figure. Chapter Three analyzes the Burlesque poetry of Francesco Berni and his challenge to the established Petrarchan love lyric. By portraying transgressive figures such as the ugly woman and the sodomite, he destabilizes the figure of the female beloved that was so venerated in the Renaissance. In addition, his use of common household objects as protagonists of his poetry produces grotesque imagery that offers rich interpretive meanings and linguistic variants. Chapter Four discusses the portrayal of the supernatural in Torquato Tasso’s Gerusalemme Liberata and Il Messaggiero. I contend that these two works show opposing attitudes towards the roles of angels and demons and how they appear to humans on earth. This dissertation evaluates the importance of monstrosity, metamorphoses and physical deformity in Renaissance society in opposition to established Neoplatonic ideals of beauty.