Left is Chief Standing Bear (as 'Chief Last Elk') in a screen capture from Chapter 1 of the Tom Mix serial, THE MIRACLE RIDER (Mascot, 1935).

The Aktá Lakota Museum and Cultural Center in South Dakota has a biography of Luther Standing Bear - he was born 1868 at the Pine Ridge Reservation in South Dakota to an Oglala Lakota family.

He was educated at the Carlisle Indian Industrial School in Carlisle, Pennsylvania, and in the early 1900s, he toured with the Buffalo Bill Wild West Show. In his later years, he was a noted lecturer, teacher, and author on Native American culture and history. He appeared in some silent and sound films, generally portraying a Native American. He also was technical advisor on a few films.

According to his death certificate, Luther Standing Bear was Sioux; born about 1860 at the Sioux Reservation, Fort Robinson, Nebraska; was widowed; and lived in Hungtington Park, Los Angeles County, California. He passed away on February 20, 1939 due to myocarditis and coronary heart disease. Funeral director was Pierce Bros. and burial at Hollywood Cemetery.

Photo and death notice for Chief Luther Standing Bear in the February 22, 1939 Hollywood Citizen-News. Excerpt: "Cecil DeMille sent Standing Bear home Monday from the 'Union Pacific' set at Paramount, when he noticed the chief was ill. Later, Standing Bear died from a heart attack ...": https://www.newspapers.com/article/los-angeles-evening-citizen-news-death-n/124452838/

Death notice for Chief Luther Standing Bear in the February 23, 1939 Carlisle, Pennsylvania The Sentinel newspaper. Notes that he was Sioux and educated at the Carlisle Indian Industrial School: https://www.newspapers.com/article/the-sentinel-death-notice-for-chief-luth/124452018/

Find A Grave website has a photo of the marker for Chief Luther Standing Bear (1868 - 1939) at Hollywood Forever Memorial Park, Los Angeles: https://www.findagrave.com/memorial/7932

  Although some of the data is incomplete or inaccurate, the Internet Movie Database (IMDb) has information on Chief Standing Bear: https://www.imdb.com/name/nm0822052/

Carlisle Indian School student record on Luther Standing Bear: https://carlisleindian.dickinson.edu/student_files/luther-standing-bear-kills-plenty-student-file

The Santa Clarita Valley History website has a 1920s photo of Chief Standing Bear and William S. Hart: https://scvhistory.com/scvhistory/lw3023.htm

Wikipedia biography of Luther Standing Bear: https://en.wikipedia.org/wiki/Luther_Standing_Bear

The Indian Actors Association was founded by Luther Standing Bear: https://en.wikipedia.org/wiki/Indian_Actors_Association

William F. Cody Archive, Buffalo Bill Center of the West and University of Nebraska-Lincoln has photos and articles about Luther Standing Bear.
Large photo postcard circa 1903 of Standing Bear: https://codyarchive.org/images/view/postcards/wfc.img.pc.0010
This link will take you to their search page: https://codyarchive.org/search/

Aktá Lakota Museum and Cultural Center, Chamberlain, South Dakota, has a bio on Luther Standing Bear: https://aktalakota.stjo.org/artists-authors/luther-standing-bear/