Michael David Pfeifer (born May 18, 1937) is the Roman Catholic bishop emeritus of the Diocese of San Angelo. He was born in Alamo, Texas, the son of Maund Pfeifer and Alice Clausney Savage. On December 21, 1964 he was ordained a priest for the Missionary Oblates of Mary Immaculate and served as a missionary in Mexico for several years. On May 31, 1985, Pope John Paul II named him Bishop of San Angelo; he was consecrated on July 26 of the same year.
Pfeifer has taken a vocal stand against the use of embryonic stem cells instead promoting the use of adult stem cells.
In accordance with canon law, Pfeifer submitted his resignation letter to then Pope Benedict XVI on his 75th birthday on May 18, 2012. Pfeifer said he would remain dedicated to serve his community in the interim before a new bishop is selected.
Pope Francis accepted Pfeifer's resignation on December 12, 2013.