Castle Peak, Mountain summit on the border of Gunnison County and Pitkin County, United States

Castle Peak is a mountain summit on the border between Gunnison County and Pitkin County in Colorado. It rises to about 14,265 feet (4,348 meters) and sits within the Elk Mountains, featuring rocky ridgelines and steep faces of exposed stone.

Castle Peak was first documented during the Hayden Survey of 1873, one of the major efforts to map the American West after the Civil War. The survey produced some of the earliest detailed maps of the Colorado high country.

Castle Peak belongs to a group of Colorado summits that rise above 14,000 feet (4,267 meters), known locally as "Fourteeners." Climbing all of them is a long-standing tradition in the state, and many hikers come here specifically to check this peak off their list.

Two standard routes lead to the summit: the Northwest Ridge, a moderate snow climb followed by an easy ridge scramble, and the Northeast Ridge, an easy snow climb with harder scrambling and route-finding. Both are rated Class 2. The Northwest Ridge should not be attempted late in summer, when 200 feet (60 m) of loose dirt and scree meet climbers near the top of the Castle-Conundrum saddle. The best climbing months are June through September, via the Montezuma Glacier snowfield between Castle and Conundrum Peaks.

Conundrum Peak, Castle Peak's northern subsummit, rises to 14,040+ feet (4,279+ m) but has only 200 feet (61 m) of clean topographic prominence, below the usual 300-foot (91 m) threshold for a separate peak. It lies 0.4 miles (0.6 km) north of Castle Peak and is often climbed together with it.