The famous philosopher known for his work "The Republic" is Plato. Living in ancient Greece around the 4th century BCE, Plato was a student of Socrates and the teacher of Aristotle. "The Republic" is one of his most significant dialogues, exploring justice, the ideal state, and the philosopher-king concept. Through the character of Socrates, Plato examines what a just society would look like and how individuals can achieve the good life. His ideas laid the foundation for Western philosophy and political theory, influencing subsequent generations in their thoughts about morality, governance, and human nature.