This dissertation is a study of ancient Greek biographies of philosophers. The pronounced ethical component of Greek philosophy meant that biography, which centered on the subject’s ethos, was an ideal venue for philosophical communication and argumentation. The dissertation collates nearly all the philosophers’ biographies of Greek antiquity (many of which are fragmentary), argues for their coherence as a literary tradition of philosophical writing, and places them within the context of the history of philosophy. Chapter One, “The Wise and the Wisdom-Lover: A Prehistory of Philosophical Biography,” traces the prehistory of philosophical biography from the moralizing apothegms of the Seven Sages to the Socratic dialogues of Plato, Xenophon, and others, showing that Socrates provided his students with the impetus for the literary focus on the life as an ethical whole. Chapter Two, “An Industry of Dissent: The First Bioi in the School of Aristotle and Beyond,” explores the development of the bios (biography) as a literary mode at the Peripatos. In response to the idealizing encomia of Plato by his students, the Peripatetics Aristoxenus, Hermippus, and Phaenias, as well as others outside the school of Aristotle, seem to provide a more critical picture of Plato and Socrates. The chapter argues for a relationship between Peripatetic bioi and peri biōn literature. Chapter Three, “Documenting the Past: Hellenistic Successions Literature and Its Imperial Revival,” identifies a shift in the late Hellenistic and early Imperial periods toward encyclopedic works that preserved and systematized philosophical history after the decline of the Athenian schools. These distinctly Alexandrian works, known as Successions of the Philosophers, present philosophy as a study of the past. Chapter Four, “The Neoplatonic Revival: Holy Philosophers and Spiritual Lives,” examines the resurgence of monographic philosophical biography in the mid-third century, as Neoplatonists wrote the Lives of their teachers and associates in order to shape their own philosophical identity and assert institutional continuity.