Boasting Sam (died 26 June 1876) was a Sioux scout of the US Army. Born in Montana, he was hired as a guide for the US 7th Cavalry Regiment during the Great Sioux War, and he reported on the location of the Sioux town of Medicine Tail Coulee, leading to George Armstrong Custer's attack on the village. Boasting Sam would be killed at some point in the ensuing battle with the Sioux.