The artist known for co-founding the Cubist movement is Pablo Picasso. Along with Georges Braque, Picasso pioneered this revolutionary art style in the early 20th century, which sought to break away from traditional perspectives and represent subjects from multiple viewpoints simultaneously. This innovative approach transformed the portrayal of form and space in painting, leading to a significant shift in artistic expression. Picasso's work in Cubism, exemplified by masterpieces like "Les Demoiselles d'Avignon," not only challenged conventions but also laid the groundwork for many modern art movements that followed.