Paul J. Kosmin (born 1984) is a historian of the Hellenistic period, the centuries after the conquests of Alexander the Great that saw the spread of Greek culture and language across the Eastern Mediterranean and western Asia. His main focus is the Seleucid Empire, the Macedonian successor state that ruled Syria, Babylonia, Persia, and various adjoining regions at its height. He is a professor of classics at Harvard University in Cambridge, Massachusetts.