Napoleon Hill was an American author, lecturer, and success writer whose work helped shape the modern fields of personal development, achievement psychology, motivational literature, and prosperity thinking. Best known for Think and Grow Rich, Hill developed a system of success principles centred on definite purpose, disciplined thought, self-confidence, persistence, organised planning, and association with ambitious, capable people. His books and lectures drew on the language of business success, self-improvement, New Thought, and practical motivation, making him one of the most recognisable figures in twentieth-century success literature.Hill's influence extends across entrepreneurship, sales training, leadership writing, wealth-building literature, and the broader self-help tradition. Though later readers and historians have debated aspects of his biography and some of his claims, the continued popularity of Think and Grow Rich is undeniable: the book remains a central text for readers seeking classic advice on ambition, prosperity, financial independence, goal-setting, and the mental habits associated with achievement.