Heidegger gives us a distinctive and new way to think about what sorts of things we are. He calls us ‘Dasein’ (literally, ‘there-being’), deliberately avoiding more traditional ways of addressing us—including as persons, consciousnesses, rational agents, and even (in Being and Time, largely) human beings. If, ex hypothesi, the human being and Dasein are not identical, then in principle there can be human beings (e.g., human babies) who are not cases of Dasein and cases of Dasein who are not human. I explore the latter possibility by asking what it would take for a posthuman entity to be a case of Dasein. I consider the extreme case of Doctor Manhattan, from Alan Moore’s Watchmen. Is Doctor Manhattan vulnerable in the same ways that a case of Dasein is or has he transcended Dasein’s distinctive finitudes? Asking after the possibility of posthuman Dasein in this way brings into relief the distinction and relationship between Dasein and the human being and allows us to identify those finitudes that belong to us qua Dasein as opposed to qua human beings.