Episcopal bishop Thomas F. Gailor was born at Jackson, Mississippi, the son of Frank Marion Gailor and Charlotte Moffett. He graduated from Racine College, Wisconsin, in 1876, and then entered the General Theological Seminary, New York City. Gailor received his S.T.B. degree from General in 1879, and in that same year his M.A. from Racine. He was ordained deacon in May 1879 and began his ministry at Messiah Church, Pulaski, Tennessee. He was ordained priest in September 1880 and in 1882 became professor of ecclesiastical history and polity at the Theological Department of the University of the South, a position he held until 1893. From 1883 until 1893, Gailor was the second chaplain of the university, replacing William Porcher DuBose. Over the years Gailor and the University of the South became synonymous. From August 1890 until July 1893, he was fourth vice-chancellor of the university.
Gailor also became synonymous with the Diocese of Tennessee. On July 25, 1893, he was consecrated assistant bishop of Tennessee, and in February 1898 he became the third bishop. He served as eighth chancellor of the university from 1908 until his death.
Gailor also held leadership positions in the national Episcopal Church. In 1916 he was elected chairman of the House of Bishops and elected president of the National Council of the Episcopal Church in 1919. He held this last position to the end of 1925.
In 1885 Gailor married Ellen Douglas Cunningham of Nashville, and they had four children.