William P. Gottlieb. I pulled hundreds of his Kodachrome slides out of a dumpster a few years ago, and I've been fascinated with them ever sense. Quite different from most of his published work.
I also have to mention W. Eugene Smith, David Douglas Duncan, Laszlo Moholy-Nagy, Bernd and Hilla Becher, Garry Winogrand, Vivian Maier, Ralph Eugene Meatyard, David Doubilet, a bunch of modern urbex and architectural photographers, and
>>3997629, desu.