This article argues that the medieval Scandinavian valkyrie and shield-maiden, overlapping categories of warrior, are best understood as a third gender, a hybrid of masculine and feminine attributes. Found in a variety of texts, myths, and legends of heroes, for example, these figures are clad in masculine attire, armor, and weapons, and exercise masculine power as they fight and choose who will die in battle. At the same time, linguistic markers, literary devices, and other of their activities mark them as feminine. The article further argues that the shield-maiden who chooses a male spouse subsequently transitions from the third gender to the feminine gender. As a consequence, she loses many of the powerful abilities of a warrior woman, along with her armor and weapons. Furthermore, her subjectivity is altered so that it is founded and dependent on that of her husband. When he dies, she is left with a diminished social network that, given the construction of subjectivity in this medieval context, leaves her personhood diminished as well.