Ernst Troeltsch (February 17 1865 – February 1 1923) was a German Protestant theologian and writer on philosophy of religion and philosophy of history, and an influential figure in German thought before 1914. His work was a synthesis of a number of strands, drawing on Albrecht Ritschl, Max Weber's conception of sociology, and the Neo-Kantians of the Baden school.

While religious thinking in the days of the Weimar Republic moved away from his direction, Troeltsch is still important in relation with the sociology of religion.