The Greek philosopher who taught Alexander the Great was Aristotle. A student of Plato, Aristotle made significant contributions to various fields, including philosophy, science, and ethics. He influenced Alexander not only in intellectual pursuits but also in the practical applications of knowledge in leadership. Under Aristotle's tutelage, Alexander developed critical thinking and an appreciation for the arts, science, and philosophy. This education enriched Alexander's outlook and profoundly shaped his later approach as a ruler, emphasizing a blend of Hellenistic culture and governance.