Immanuel Kant: Kant is known for his deontological ethics and his emphasis on reason and morality. He believed that morality should be based on duty rather than consequences, and that people have inherent worth and should never be treated merely as means to an end.

Friedrich Nietzsche: Nietzsche is known for his critiques of traditional morality and religion, and his advocacy of individualism and the "will to power". He believed that people should strive to become "supermen" or "Übermensch" who create their own values and live according to their own rules, rather than following those imposed by society.

Plato: Plato is known for his theory of Forms or Ideas, which posits that there are eternal and unchanging abstract entities that exist beyond the physical world. He believed that knowledge and truth are attainable through reason and dialectic, and that philosophers are the only ones capable of ruling justly.

Aristotle: Aristotle is known for his philosophy of virtue ethics and his emphasis on empirical observation and rational inquiry. He believed that happiness or eudaimonia is the ultimate goal of human life, and that it can be achieved through the cultivation of virtues such as courage, wisdom, and justice.