John Muir (April 21, 1838 – December 24, 1914), also known as "John of the Mountains" and "Father of the National Parks", was a Scottish-born American  naturalist, author, environmental philosopher, botanist, zoologist, glaciologist, and early advocate for the preservation of wilderness in the United States. His letters, essays, and books describing his adventures in nature, especially in the Sierra Nevada, have been read by millions. His activism helped to preserve Yosemite Valley and Sequoia National Park, and his example has served as an inspiration for the preservation of many other wilderness areas.

Source: Wikipedia