Before his appointment as sixth Bishop of San Angelo on December 12, 2013, the Most Rev. Michael J. Sis was the Vicar General and the Moderator of the Curia for the Diocese of Austin. He was appointed by Bishop Joe S. Vasquez in June of 2010.

Bishop Sis grew up in Bryan. He is the son of Raymond and Janice Sis. Born on January 9, 1960, he is the fourth of five children. He attended St. Joseph Catholic School and Bryan Public Schools in Bryan. 

He graduated from Bryan High School in 1978. He earned an undergraduate degree in Philosophy in 1982 from the University of Notre Dame in South Bend, Ind., where he attended Moreau Seminary. 

He studied Theology at the North American College in Rome, receiving degrees from the Pontifical Gregorian University in 1985 and the Alphonsian Academy of the Pontifical Lateran University in 1990. 

He was ordained a priest of the Diocese of Austin in 1986 by Bishop John E. McCarthy. Bishop Sis served in a variety of roles in the Diocese of Austin. His first assignment was in Hispanic ministry at Cristo Rey Parish in East Austin. He assisted Bishop John E. McCarthy and Msgr. Edward C. Matocha in the administration of historic St. Mary Cathedral in downtown Austin. His longest term of service was in campus ministry at St. Mary Catholic Center at Texas A&M University in College Station, serving first as parochial vicar, then as pastor, for a total of 13.5 years. Archbishop Gregory M. Aymond then appointed him in 2006 as full-time Vocation Director for the Diocese of Austin. Then, after serving one year as pastor of the large suburban parish of St. Thomas More in Austin, he was named Vicar General and Moderator of the Curia by Bishop Joe S. Vasquez in 2010.

In his role as Vicar General and Moderator of the Curia, he assisted Bishop Vasquez as coordinator of diocesan administration and as supervisor of the secretariat directors. 

Over the years, Bishop Sis has served as a member of the Presbyteral Council, the Priest Personnel Board, the College of Consultors, the Vocation Team, the Permanent Diaconate Admissions Committee, and the Bishop's Advisory Council. He also served as Dean of the Bryan-College Station Deanery. Some of the most formative experiences that have helped shape his life of Christian faith have been the following: the training he received from his parents at home; his participation as a teenager in the religious education and CYO programs of St. Anthony Parish in Bryan; volunteer service in Big Brothers/Big Sisters of America; his academic and seminary studies; a summer of volunteer missionary service in Tanzania, East Africa; working with Ethiopian refugees in Rome; teaching religion at Marymount International School in Rome; making the Spiritual Exercises of St. Ignatius of Loyola; celebrating the Catholic sacraments as a parish priest, especially Confession and the Eucharist; pastoral ministry with Hispanic immigrants in Texas; campus ministry with the students of Texas A&M; ecumenical and interreligious collaboration; the Cursillo and Awakening retreats; assisting in the formation of seminarians; the good example of fellow priests; the influence of friends; and the experience of spiritual direction. He considers his most precious treasure to be his personal relationship with Jesus Christ.