The foundational premise of this work is that the concept of individual moral agency that underlies contemporary ethical discourse rests on a flawed model of selfhood inherited, in most cases unwittingly, from the Enlightenment; particularly from the efforts of the German Idealists to rebuild moral theory upon the cornerstone of human reason. The model of selfhood they provide carries with it a number of conceptual difficulties that prove fatal to any attempt to construct a unified and comprehensive theory of ethics – specifically the problems of relating the subjective to an objective reality, the nature of temporal existence, the challenge of nihilism, and a seemingly inevitable doctrine of conflict between self and Other. However, these problems did not escape the notice of those philosophers of the phenomenological tradition that we now identify as existentialists. Unfortunately, none of the existentialists, either, met with any greater success in finding a way from the existent self to a working theory of intersubjective ethics. Indeed, their unique awareness of, and focus on, the specific difficulties confronting that project has often resulted in a far clearer sense of failure than we are accustomed to admitting to in contemporary ethics. My primary contention is that, by observing the treatment of selfhood through the works of a selection of the most prominent existentialists – Kierkegaard, Nietzsche, and Jean-Paul Sartre – and examining both the manner in which each stumbles in reaching towards intersubjective ethics and the solutions they offer to the failures that precede them, we might identify a set of desiderata that would helpfully inform any new theory of existentialist ethics. For the most part, the metaphysical commitments of each theorist are drawn directly from their primary works, but, in the case of the infamously obscurantist Nietzsche, no clear statement exists in the primary literature. We will, therefore, rely on a promising contemporary analysis drawn principally from the discourse between John Richardson and Paul Katsafanas. I will argue that, viewed together, these desiderata may at least suggest a possible path forward in the form of a shift away from the substance ontology that underlies the Idealist position towards a form of process phenomenology.