This text presents a critical synthesis of the thought of Hans Jonas (1903-1993), a philosopher of Jewish origin and former pupil of M. Heidegger and R. Bultmann in Marburg, who in 1933 fled from Nazi Germany to Palestine, Canada and finally settled in the USA. Jonas authored significant works on late-antique Gnosticism, the philosophy of life, philosophical anthropology, the ethics of responsibility, bioethics, and speculative theology. The book also proposes a comprehensive and innovative interpretation of Jonas’ thought in terms of a deep and relentless commitment to the future, in face of the perils of contemporary nihilism and present-day technology.  The intrinsic complexity and heterogeneity of Jonas’ philosophical interests is probably the reason why a comprehensive and critical reconstruction of his thinking has yet to be carried out successfully in the English language. This book fills that gap.  By doing so, the authors clarify the role played by Jonas in the philosophy of the 20th century but also shed light on the possible contribution of his insights to present-day debates regarding science, ethics, bioethics, and politics. The authors argue that within the heterogeneity of his work reverberates a unitary and coherent existential attitude, which explains both his deep interest in life and his personal engagement in the preservation of its integrity. This work appeals to researchers and students in philosophy seeking to become more acquainted with the scholarship of Hans Jonas.