Castle Mountain (12,617 feet (3,846 m)) is in the Beartooth Mountains in the U.S. state of Montana, about 15 miles (24 km) east-northeast of Cooke City. It is located in the Gallatin National Forest and Custer National Forest, just outside the northern boundary of Yellowstone National Park in the Absaroka–Beartooth Wilderness.

The peak is the third tallest in the Beartooth Mountains, and the highest point in Carbon County, Montana.