The Crazy Mountains, often called the Crazies, is a mountain range in the Central Montana Alkalic Province in the U.S. state of Montana. They are a part of the northern Rocky Mountains.

Spanning a distance of 40 miles (64 km), the Crazy Mountains are located between the Musselshell and Yellowstone rivers. The highest peak is Crazy Peak at 11,214 feet (3,418 m). Rising over 7,000 feet (2,130 m) above the Great plains to the east, the Crazies dominate their surroundings and are plainly visible just north of Interstate 90.

The Crazy Mountains form an isolated island range east of the Continental Divide. Other isolated ranges in Montana include the Castle Mountains, Little Belt Mountains, Big Snowy Mountains, Little Snowy Mountains, Bears Paw Mountains, Judith Mountains, North and South Moccasin Mountains, Highwood Mountains, Little Rocky Mountains, Sweet Grass Hills, Bull Mountains and, in the southeastern corner of the state near Ekalaka, the Long Pines.

Due to the eastern location, these mountains are drier and less densely forested than other mountain ranges in Montana. There are at least 40 alpine lakes in the range, 15 of which are named. The Crazy Mountains sit in both Gallatin National Forest and Lewis and Clark National Forest. The Crazies support a healthy herd of mountain goats and the occasional elusive wolverine.

In 1916, the Crazy Mountains were proposed as a location for a national park, but Congress failed to pass the legislation. National Park Service officials considered the area again in 1935, but reported that a national park would not be feasible because "half of the land, every alternate section, is owned by the Northern Pacific Railroad or is in private hands."^[2]

The Crazies are almost completely surrounded by private lands making access into the mountains somewhat difficult, especially in the southern section where the highest peaks are located.^[3][4]

The name Crazy Mountains is said to be a shortened form of the name "Crazy Woman Mountains" given them, in complement to their original Crow name, after a woman who went insane and lived in them after her family was killed in the westward settlement movement.^[5]

The Crow people called the mountains Awaxaawapìa Pìa, roughly translated as "Ominous Mountains", or even more roughly, "Crazy Mountains". They were famous to the Crow people for having metaphysical powers and being unpredictable—a place used for vision quests.^[6]

• List of mountain ranges in Montana