Mount Massive (Arapaho: Hiwoxuu hookuhu'ee) is the second-highest summit of the Rocky Mountains of North America and the U.S. state of Colorado.

It is located in the Mount Massive Wilderness of San Isabel National Forest, 10.6 miles (17.1 km) west-southwest (bearing 247°) of the City of Leadville in Lake County, Colorado, United States.

[7] Its name comes from its elongated shape: it has five summits, all above 14,000 ft (4,300 m), and a summit ridge over 3 mi (4.8 km) long, resulting in more area above 14,000 ft (4,300 m) than any other mountain in the 48 contiguous states, narrowly edging Mount Rainier in that category.

The lower slopes of the mountain are covered in lodgepole pine forests, which gradually yield to Engelmann Spruce and Fir.

In the Arapaho Language the Collegiate Range and Mount Massive are called Hiwoxuu hookuhu'ee or Elk's Head.