Friedrich Nietzsche was a German philosopher, cultural critic, and poet who lived in the late 19th century. His work was characterized by an emphasis on individualism, the rejection of traditional morality, and the affirmation of life. Nietzsche's concept of the "will to power" suggested that all human actions are motivated by a desire for power and dominance, and he believed that individuals should strive to achieve their full potential and create their own values.