Robert Kayen is an American rock climber best known for completing the first solo ascent of El Capitan‘s West Buttress in Yosemite National Park in 1982. The eleven-day rope-solo climb followed the original route on the West Buttress, first climbed by Layton Kor and Steve Roper in 1964. Kayen skied the first winter traverse of the Sierra Nevada Mountains along a four hundred mile route between Mount Whitney and Lake Tahoe in 1984 and 1985, skiing via the John Muir Trail and the high-elevation portions of the Tahoe-Yosemite Trail.