Castle Peak is the ninth highest summit of the Rocky Mountains of North America and the U.S. state of Colorado. The prominent 14,279-foot (4352.2 m) fourteener is the highest summit of the Elk Mountains and the Maroon Bells-Snowmass Wilderness. The peak is located 11.6 miles (18.7 km) northeast by north of the Town of Crested Butte, Colorado, United States, on the drainage divide separating Gunnison National Forest and Gunnison County from White River National Forest and Pitkin County. The summit of Castle Peak is the highest point of both counties.

In the mountaineering parlance of the Western United States, a fourteener is a mountain peak with an elevation of at least 14,000 ft (4267 m). The 96 fourteeners in the United States are all west of the Mississippi River. Colorado has the most (53) of any single state; Alaska is second with 29. Many peak baggers try to climb all fourteeners in the contiguous United States, one particular state, or another region.