Russell Means, to director Michael Mann, had always symbolized the courage and determination of indigenous people fighting for their rights. But before Mann cast Means in his Oscar-winning 1992 movie “The Last of the Mohicans,” he wasn’t sure if the charisma of the famed activist would translate to the big screen.

Means, an Oglala/Lakota Sioux Indian who became an activist for American Indian rights, passed away today at the age of 72 on the Pine Ridge Indian Reservation. Known for being a prominent member of the American...