Yves Klein (1928–1962) was a groundbreaking French artist whose radical ideas and iconic ultramarine pigment—International Klein Blue (IKB)—redefined postwar art. A central figure in the Nouveau Réalisme movement, Klein sought to transcend traditional art forms, creating works that explored immateriality, spiritual experience, and the void. He is best known for his monochrome blue paintings, “Anthropometries” made with the human body as a brush, and performance-based pieces that blurred the line between art and life. Despite his brief career, Klein’s conceptual approach and avant-garde vision left a profound influence on minimalism, performance art, and conceptualism.