Place and date of his birth are uncertain, he was probably born in the early 1840s near Bear Butte on the Belle Fourche River in South Dakota. The father of Crazy Horse was a medicine man of the Oglala subtribe, and his mother a BrulŽ, the sister of Spotted Tail. His mother died when he was young, and his father took her sister as a wife and she helped raise Crazy Horse. As a youth he was known as Curly, but acquired the father's name of Crazy Horse after proving himself in combat.

Crazy Horse was an imposing figure, about six feet tall. He married a Cheyenne woman, and this resulted in close ties between his band of the Sioux and the Cbeyennes. He was also, by marriage, a relative of the famous Red Cloud.