William Vandivert was an American photographer, co-founder in 1947 of the agency Magnum Photos.

Magnum Photos is an international photographic cooperative owned by its photographer-members, with offices in Paris, New York City, London and Tokyo. It was founded in 1947 in Paris by photographers Robert Capa, David "Chim" Seymour, Maria Eisner, Henri Cartier-Bresson, George Rodger, William Vandivert, and Rita Vandivert. Its photographers retain all copyrights to their own work.