Geissler Mountain is a 13,381-foot peak in Colorado’s Sawatch Range, in the Hunter–Fryingpan Wilderness near Aspen, Independence Pass, and the Continental Divide. The wilderness’s fourth-highest summit, it has higher eastern and slightly lower western tops, with the U.S. Geological Survey identifying the eastern point as the summit. Though not exceptionally prominent, it rises steeply above Lost Man Creek and Lost Man Lake and feeds the upper Roaring Fork watershed from both north and south slopes. Known in print since at least 1943 and officially recognized by the United States Board on Geographic Names, it remains a lesser-known thirteener valued for its setting, views, and hiking access.