The purpose of this thesis is to establish how American writer Sylvia Plath utilizes the non-human animal image to explore gender roles and identity. Despite the overwhelming amount of criticism that has been dedicated to Plath's writing and life, the use of non-human animals in her work has rarely been addressed. A primary focus will be on the violence and aggression evident in a large amount of her poetry, much of it aligned with gender and the non-human animal image. In examining the ways in which Plath utilizes animals, a distinction becomes apparent between the majority of her earlier writing and her later work. In Plath's earlier work, she typically uses animals within a triangular model, where the animal's significance is determined by the relationship between the male and female human protagonists. As her work develops, there is an evident shift in the role and representation of the animal images as they begin to depart from the earlier triangular model. In Plath's later work the animal representations are aligned closely with the identities of the female figures. Here, animals essentially take on a mythic, prosthetic role and enable the female figures' transcendence towards a non-victim status. Plath's shifting representations of the non-human animal acknowledge traditional gender dichotomies, but ultimately undermine them.