John Muir was a big name in conservation history. He was an American naturalist, author, and early advocate of preservation of wilderness in the United States. He is often referred to as the 'Father of the National Parks' and was instrumental in the establishment of Yosemite National Park. Muir was also a key figure in the creation of the Sierra Club, one of the most influential environmental organizations in the world. His writings and activism helped to inspire the modern environmental movement.