Magnum

Magnum is one of the first photographic cooperatives, owned and administered entirely by members. The photographers Robert Capa, David "Chim" Seymour, Henri Cartier-Bresson, George Rodger and William Vandivert were the founding members (Vice Presidents) of Magnum in Paris in 1947, based on an idea of Capa's.
The staff serve a support role for the photographers, who retain all copyrights to their own work.
The Magnum cooperative has included photojournalists from across the world, who have covered many historical events of the 20th century. The cooperative's archive includes photographs depicting family life, drugs, religion, war, poverty, famine, crime, government and celebrities.(*)
(*) from Wikipedia

http://www.magnumphotos.com/