Little Bighorn Battlefield National Monument preserves the site of the June 25 and 26, 1876, Battle of the Little Bighorn, near Crow Agency, Montana, in the United States. It also serves as a memorial to those who fought in the battle: George Armstrong Custer's 7th Cavalry and a combined Lakota-Northern Cheyenne and Arapaho force. Custer National Cemetery, on the battlefield, is part of the national monument. The site of a related military action led by Marcus Reno and Frederick Benteen is also part of the national monument, but is about 3 miles (4.83 km) southeast of the Little Bighorn battlefield.

The Battle of the Little Bighorn, known to the Lakota and other Plains Indians as the Battle of the Greasy Grass, and commonly referred to as Custer's Last Stand, was an armed engagement between combined forces of the Lakota Sioux, Northern Cheyenne, and Arapaho tribes and the 7th Cavalry Regiment of the United States Army. The battle, which resulted in the defeat of U.S. forces, was the most significant action of the Great Sioux War of 1876. It took place on June 25–26, 1876, along the Little Bighorn River in the Crow Indian Reservation in southeastern Montana Territory.