Alfred Stieglitz
Alfred Stieglitz (1864-1946) played a fundamental role establishing photography as an integral part of modern art, through his own photographs, journals he edited and published, and exhibitions he staged at his own New York galleries. See a selection of the Alfred Stieglitz Collection, housed at the Art Institute of Chicago, including some of the influential—and controversial—photographs he took of his wife, the painter Georgie O’Keefe, here.
https://archive.artic.edu/stieglitz/alfred-stieglitz/
Stieglitz’s influential photographic work covered over half a century. See 130 of his photos, spanning from 1887 to 1937, here.