This book reconstructs Heidegger's philosophy of time by reading his work with and against a series of key interlocutors that he nominates as being central to his own critical history of time. In doing so, it explains what makes time of such significance for Heidegger and argues that Heidegger can contribute to contemporary debates in the philosophy of time. Time is a central concern for Heidegger, yet his thinking on the subject is fragmented, making it difficult to grasp its depth, complexity, and promise. Heidegger traces out a history that focuses on the conceptualisations of time put forward by Aristotle, Plotinus, Augustine, Kant, Hegel, Bergson, and Husserl - an "alternative history of time" that challenges how time has been defined and studied within both philosophy and the sciences. This book explores what happens when we take seriously Heidegger's claim that these seven figures are essential to any understanding of time, setting out what this can tell us about existence, possibility, and philosophy as a historical discipline. Heidegger's Alternative History of Time will appeal to scholars and advanced students working on Heidegger, phenomenology, the philosophy of time, and the history of philosophy.