The Hidatsa, which means "People of the Willows", are a Siouan people of the federally recognized Three Affiliated Tribes residing on the Fort Berthold Reservation in North Dakota. Around one half of the population of Hidatsa reside on the Fort Berthold Reservation.

Historically, they were organized into matrilineal clans. Within each village these clans functioned as corporate groups that controlled land, arranged marriages, sponsored ceremonies and ritual feasts, and generally served to integrate the population. Depopulation, intermarriage with other tribes and with whites, and forced acculturation resulted in a breakdown of the clan system.

Their language is closely related to that of the Crow, and they are sometimes considered a parent tribe to the modern Crow in Montana. The Hidatsa people still speak Hidatsa, see Language Project.

Many Hidatsas converted to various denominations of Christianity, some have retained portions of their traditional beliefs and practices.