This essay challenges the normative textual readings bequeathed by the construct of the medieval literary canon and affirms the existence of a wide range of non-canonical Middle Ages. The transgender Middle Ages – which I theorize as a cross-temporal engagement, mobilizing the viewpoint of the modern trans subject to elucidate the traces of transgender subjectivity that inhere in certain medieval narratives – is one such non-canonical Middle Ages. Using the example of Christine de Pizan’s Livre de la Mutacion de Fortune [Book of Fortune’s Transformation] (1403), I demonstrate how the weight of the canon operates to preclude the possibility of trans readings of medieval texts, going so far as to selectively negate narrative elements in order to produce a hegemonic interpretation. The Mutacion’s narrator declares repeatedly that he is a man, yet this assertion is typically undermined by the critical viewpoint that, since narrator and author are both named Christine, they must be one and the same. The emphasis on metaphor within the text is also commonly employed in criticism to hold transness at bay, reducing it to a rhetorical flourish. I demonstrate in this essay, however, that metaphor and truth are not mutually exclusive. Further, I indicate metaphor’s deep connection to transness, and thus the way that metaphor can function not to negate but to make manifest trans identity and embodiment. This essay reclaims and celebrates complex and shifting transgender textual possibilities in all their monstrous mutability.