Above is a crop/blowup of Wilkerson as "Tonka" from a lobby card from the KING OF THE STALLIONS (Monogram, 1941).

(Courtesy of Ed Phillips)

Billy Wilkerson was born 1902 in Indian Territory (now Oklahoma) and his Native American lineage was Cherokee.

His twenty year Hollywood career spanned from the mid 1930s through the mid 1950s. His movie jobs were a mix of credited and unbilled roles and you can spot him in films such as: FRONTIER FURY (as Chief Eagle Feather), KING OF THE STALLIONS (Tonka), APACHE CHIEF (Grey Cloud), BOWERY BUCKAROOS (Moose), BROKEN ARROW (Juan), DAVY CROCKETT, INDIAN SCOUT (High Tree), TULSA (Lazy Mouse), SAGINAW TRAIL (The Fox Chief), TRAVELING SALESWOMAN (Tony), YUKON VENGEANCE (Lone Eagle), BOWERY BUCKAROOS (Big Moose), SINGING SPURS (Chief Wolfpack), and RIDING WEST (Chief Red Eagle).

1934 - 1936 records and newspaper articles have info on his pre-Hollywood years: he was involved in planning an American Indian Day for the 1933 - 1934 Chicago World's Fair ... he and Edna Mae McClung married in Cook County, Illinois in 1936 ... and he was a graduate of Bacone College, Indian school at Muskogee, Oklahoma and appointed director of the Indian division of the Republican National Committee.

  Although some of the data is incomplete or inaccurate, the Internet Movie Database (IMDb) has information on Bill Wilkerson: https://www.imdb.com/name/nm0929097/

Ancestry.com had census rolls and enrollment application for a child as a citizen of the Cherokee Nation. William Wilkerson was born September 18, 1902 in Indian Territory to Richard and Annie Wilkerson, both citizens of the Cherokee Nation.

February 1, 1936 marriage record of 33 year old William Wilkerson and 27 year old Edna Mae McClung in Cook County, Illinois: https://www.familysearch.org/ark:/61903/1:1:Q21K-6LPV

1940 census - renting in Los Angeles were 37 year old William P. Wilkerson (born Oklahoma) and his 32 year old wife Edna (born Illinois). They lived in Chicago in 1935. His race was Indian; completed 1 year of college; occupation was "Actor - Motion Picture Co."; and in 1939, he worked 20 weeks and earned $1000.00: https://www.familysearch.org/ark:/61903/1:1:K9CJ-7KL

Ancestry.com had the World War II draft registration dated February 14, 1942 for 39 year old William Wilkerson. He was born September 18, 1902 in Bartlesville, Indian Territory (now Oklahoma). He and wife Edna lived at 436 1/2 North Norton Avenue, Los Angeles; his occupation was "Free lance actor - on call - all studios"; race was Indian; and he was 5 feet, 11 inches tall and weighed 205 pounds.

The California Death Index and Social Security Death Index (SSDI) have records for William P. Wilkerson - he was born 9/18/1902 in Oklahoma, Mother's maiden name of Hendrick, and passed away on 3/3/1966:
https://www.familysearch.org/ark:/61903/1:1:VP45-B8V
https://www.familysearch.org/ark:/61903/1:1:V9T5-W6R

Find A Grave has Wilkerson and wife Edna interred next to each other at Forest Lawn Memorial Park, Hollywood Hills, Los Angeles County, California:
William Penn Wilkerson: https://www.findagrave.com/memorial/85956488/william-penn-wilkerson
Edna Wilkerson (1908 - 1972): https://www.findagrave.com/memorial/85956479/edna-may-wilkerson

Newspaper articles which confirm his Native American lineage was Cherokee:

September 2, 1934 Chicago Tribune has a large photo of Wilkerson (and others) planning an American Indian Day at the 1933-34 Chicago World's Fair: https://www.newspapers.com/article/chicago-tribune-william-p-wilkerson-was/125881651/

September 16, 1936 Santa Rosa, California Republican paper has an article on William P. Wilkerson, Cherokee, appointed director of Indian division of Republican National Committee ... and he was a graduate of Bacone College, Indian school at Muskogee, Oklahoma: https://www.newspapers.com/article/santa-rosa-republican-william-p-wilkers/125875759/

October 24, 1941 San Fernando, California Valley Times has an article on Cherokee lecturer and Republican National Committee Indian division member doing a program about horses and the history of Native Americans in Southern California: https://www.newspapers.com/article/san-fernando-valley-times-cherokee-lectu/125876178/

March 26, 1956 Los Angeles Evening Citizen News has a lengthy article on Wilkerson playing Indian roles as well as being a technical advisor on films and TV. He was working on the Rin-Tin-Tin TV program: https://www.newspapers.com/article/los-angeles-evening-citizen-news/125876770/