The ancient Greek philosopher known for his ideas on ethics is Aristotle. Aristotle was a student of Plato and a teacher of Alexander the Great. He developed a comprehensive ethical framework that explored the nature of virtue, morality, and the good life. In his work "Nicomachean Ethics," Aristotle discussed concepts such as virtue ethics, the doctrine of the mean, and the importance of cultivating moral character to achieve eudaimonia, which can be translated as "flourishing" or "living well." Aristotle's ethical philosophy has had a significant influence on Western moral thought and continues to be studied and debated to this day.