The Lesser Slave River (Cree Iyaghchi Eennu Sepe, translation: "River of the Strange People"[1]) is a river in central Alberta, Canada. It is a major tributary of the Athabasca River.
The Lesser Slave Lake and the river were the main links to the Peace River district until the beginning of the 20th century, when the construction of the Northern Alberta Railway facilitated transportation in the area.[2]