Jean-Paul Sartre is the prominent French philosopher associated with existentialism, a philosophical movement emphasizing individual existence, freedom, and choice. His works, including "Being and Nothingness," explore the meaning of existence and the absurdity of life. Sartre's ideas challenged traditional notions of morality and prompted discussions on authenticity and self-creation. His influence extends beyond philosophy to literature and political thought, as he advocated for social change and engaged with the challenges of modern existence.