Ansel Easton Adams (February 20, 1902 – April 22, 1984) was an American landscape photographer and environmentalist known for his black-and-white images of the American West.

Adams was a life-long advocate for environmental conservation, and his photographic practice was deeply entwined with this advocacy. For his work and his persistent advocacy, which helped expand the National Park system, he was awarded the Presidential Medal of Freedom in 1980.

He was a key advisor in establishing the photography department at the Museum of Modern Art in New York, an important landmark in securing photography's institutional legitimacy. He helped to stage that department's first photography exhibition, helped found the photography magazine Aperture, and co-founded the Center for Creative Photography at the University of Arizona.