The prominent philosopher known for their exploration of utilitarian ethics is John Stuart Mill. Mill expanded on the ideas of earlier utilitarian thinkers, advocating that the best actions are those that promote the greatest happiness for the greatest number. His influential work, "Utilitarianism", addresses the moral implications of actions based on their consequences for overall happiness. Mill's utilitarianism significantly shaped modern ethical discussions, providing a framework for evaluating morality based on outcomes and societal welfare, influencing various fields including politics and economics.