Mary McClellan O'Hair, the first woman regent of the University of Texas, was born in Burton, Texas, in 1869, the daughter of W. R. and Louisa (Ratliff) McClellan. She grew up in Washington County and attended public schools in Brenham before entering Baylor Female College in Independence (now the University of Mary Hardin-Baylor in Belton), where she received a bachelor's degree in 1886. The following year she married wealthy rancher H. J. O'Hair in Ledbetter, Texas. The couple had a daughter who died as an infant and a son who died during the influenza epidemic of World War I. The O'Hairs lived briefly in Lockhart before moving to Coleman. Influenced by her father, who was a two-term member of the Texas legislature, O'Hair was an early supporter of woman suffrage and a member of the Daughters of the American Revolution and the Daughters of the Republic of Texas. She served as president of the Texas Woman's Press Association in 1910 and remained an active member of that organization the rest of her life. In Coleman she organized the first Self Culture Club, which helped women find opportunities for self-improvement, and promoted study clubs and the local public library. She also served as president of the City Federation of Women's Clubs in Coleman and was active in the local Christian church. During World War I she lived in New York City for several months to assist in the war effort, and she was honored by the Canadian Red Cross for her help with war work in Canada.
In May 1921 Governor Pat M. Neff appointed Mary O'Hair to a six-year term as a regent of the University of Texas. She subsequently was selected by Governor Dan J. Moody to complete an unexpired two-year term, thus becoming the first regent ever to be reappointed. While on the board, as a member of the building and grounds committee, she advocated replacing temporary structures on the university campus with permanent buildings. Her service as a regent coincided with a $1.3 million appropriation from the state legislature for campus expansion. O'Hair, who was appointed forty years after the first board of regents was named, was the only woman to serve on the board of regents until 1935, when Governor Miriam A. Ferguson appointed Marguerite Shearer Fairchild of Lufkin. Other regents who served with O'Hair included H. J. Lutcher Stark, philanthropist and businessman, and Judge Robert Batts, former United States circuit judge. O'Hair completed her service on the board of regents in 1929. In her retirement she continued her activities for charitable organizations and traveled extensively. She died in Coleman on December 4, 1936, after a long illness, and was buried there. She was survived by her husband, two siblings, a grandson, and a nephew. At her death flags at the Capitol were lowered to half mast in her memory.