While the lone wolf artist has long been romanticized for its singular (if not god-given) genius, the creative duo has also, many times over, recast the shape of art. Below, we explore seven of art history’s game-changing partnerships during the 20th century. For these pioneering artists—from Christo and Jeanne-Claude to Marina Abramovic & Ulay—collaboration was an integral, motivating agent in the development of their practices, which span monumental sculpture, endurance-testing performance, and innovative digital art.