Edmund Viesturs (born June 22, 1959) is a high-altitude mountaineer and corporate speaker. He is the only American to have climbed all 14 of the world's eight-thousander mountain peaks, and the fifth person to do so without using supplemental oxygen. Along with Apa Sherpa, he has summitted peaks of over 8,000 meters on 21 occasions, including Mount Everest seven times; only four other climbers, Phurba Tashi Sherpa Mendewa, Juanito Oiarzabal, Namgyal Sherpa, and Ang Dorje Sherpa, have more high-altitude ascents.