Marcella LeBeau was born on October 12, 1919, on the Cheyenne River Indian Reservation. As a child, she attended an Indian boarding school. She earned her undergraduate degree in nursing in 1942 from St. Mary’s Hospital in Pierre, South Dakota.
After graduation, LeBeau began working as a registered nurse in Pontiac, Michigan. In 1943, she enlisted in the United States Army Nurse Corps to serve in World War II. LeBeau served in France, England, and Belgium under the 76th General Hospital unit, including at the Battle of the Bulge. She left the Army as a First Lieutenant.
When her service ended, she returned to South Dakota and worked for the Indian Health Service (IHS) serving as director of nursing at the IHS facility in Eagle Butte, South Dakota. She worked for IHS for 31 years before retiring. As a result of her medical career, she received the O. Marie Henry RNDNSC Chief Nurse and the Mable Ann Wagner Award.
In 1991, she was elected to the Cheyenne River Sioux Tribal Council. During her tenure on the council, LeBeau banned smoking in tribal chambers and promoted other anti-smoking policies. LeBeau’s anti-smoking efforts on the Cheyenne River Indian Reservation are credited with helping the reservation become the first smoke-free community in South Dakota.
In 2004, LeBeau was awarded the Legion of Honour for her World War II service. LeBeau was awarded the Women in History Award from the Spirit of the Prairie Chapter of the Daughters of the American Revolution in 2016. LeBeau also has an honorary degree from South Dakota State University.
On October 12, 2019, she celebrated her 100th birthday; the date was proclaimed Wígmuŋke Wašté Wíŋ (Pretty Rainbow Woman) Marcella LeBeau Day by the state of South Dakota, receiving a Senatorial Tribute from Senator John Thune.
LeBeau supported the Remove the Stain Act in the United States Congress, which seeks to rescind the medals of honor awarded to American soldiers who participated in the Wounded Knee Massacre. In 2019, she spoke at a ceremony to introduce the bill, alongside Deb Haaland, at the U.S. Capitol.
In 2020, LeBeau was awarded a Leadership Award from the National Congress of American Indians. She died on November 21, 2021, at the age of 102.