Edmund Viesturs (born June 22, 1959) is a high-altitude mountaineer and corporate speaker. He is the only American to have climbed all fourteen of the world's eight-thousander mountain peaks, and the fifth person to do so without using supplemental oxygen. He has summited peaks of over 8,000 meters on 21 occasions, including Mount Everest seven times; only two other climbers, Phurba Tashi Sherpa Mendewa and Juanito Oiarzabal, have more high-altitude ascents.