The ancient Greek philosopher who taught Alexander the Great was Aristotle. A student of Plato, Aristotle is known for his vast contributions across numerous fields including philosophy, ethics, and natural sciences. He began teaching Alexander at the age of 13, imparting knowledge in subjects such as politics, literature, and science. This education had a substantial influence on Alexander’s later approach to leadership and conquest, shaping his vision of a culturally integrated empire. Aristotle’s teachings laid the foundation for many Western philosophical traditions.