The famous philosopher known for their contributions to social contract theories is Jean-Jacques Rousseau. Rousseau's work, particularly in "The Social Contract", outlines the idea that legitimacy of authority comes from the consent of the governed. He argued for the importance of the collective will and the concept of popular sovereignty. His ideas had a profound influence on political theory, shaping democratic principles and inspiring revolutions. Rousseau's explorations of individual freedom versus societal obligation continue to resonate in contemporary philosophical and political discussions.