What is a person? This question often arises today in debates about the beginning and end of human life: when, e.g., does a fetus becomes a person, and at what stage of brain death does a body ceases to be a person? In the 13th-14th centuries, there were also lively and broad-ranging discussions about the nature of persons. In the social-political realm, the juridical notion of 'person' stressed the idea of inherent dignity and rationality. In logical and grammatical discussions, 'person' was used to indicate individuality (as opposed to universality or commonality). In theological contexts, 'person' was a term used most often in Trinitarian and Christological debates: God was three persons in one Being, and Christ was one person with two natures (human and divine). In this talk, I address how these three contexts for discussions of persons in the Middle Ages intersect in the work of 13th-15th century mystics, such as Hadewijch, Meister Eckhart, and Catherine of Siena. The focus on first-personal narratives and self-knowledge in the contemplative tradition combines with ideas about dignity and a highly complex understanding of individuality to yield a concept of 'person' that has room for embodied human beings, immaterial angels, and a triune God. I argue that the resulting discussions also prefigure both early modern and contemporary notions of persons, as well as playing an important role in the development of the theory of personalism.