Mary Ignatia Gavin, C.S.A., (January 1, 1889 – April 1, 1966) was an Irish-born American Religious Sister, better known as Sister Ignatia, belonging to the Sisters of Charity of St. Augustine, who served as a nurse. In the course of her work she became involved in the care of those suffering from alcoholism, working with Dr. Bob Smith, a co-founder of what became Alcoholics Anonymous. In this work she became known as the alcoholic's "Angel of Hope".
She was born Bridget Della Mary Gavin on 1 January 1889 to Barbara Neary and her husband, who lived on a small parcel of farmland called Gavin's Field in Shanvalley, Burren, County Mayo, Ireland, then part of the United Kingdom of Great Britain and Ireland. Having moved to the United States, in 1914 she entered the Sisters of Charity of St. Augustine in Ohio, at which time she was given the religious name of Sister Mary Ignatia. A superb musician, she was assigned to teach music. She did this for about ten years, but found it "too hectic" and suffered a nervous breakdown. When she recovered, she was assigned by her religious congregation to work in the admissions office of St. Thomas Hospital in Akron, Ohio.
By the 1930s, Gavin was in charge of admissions at the hospital. Despite its policy of not treating "drunks", she began to do so furtively in 1934. On August 16, 1935, armed with a medical diagnosis of acute gastritis issued by Smith, who was a courtesy staff member of the hospital, she admitted an alcoholic patient to the hospital, making it the first in the world to treat alcoholism as a medical condition. That patient would be the first of millions to participate in the Twelve-step program of recovery, the beginning of Alcoholics Anonymous.