Antônio de Castro Mayer (20 June 1904 – 25 April 1991) was a Brazilian prelate of the Roman Catholic Church. A Traditionalist Catholic and ally of Archbishop Marcel Lefebvre, he was Bishop of Campos from 1949 until his resignation in 1981. He is often described as incurring the automatic canonical penalty of excommunication for participating in the 1988 illicit consecration of four bishops of the Society of St. Pius X (SSPX), as did Lefebvre and the four bishops then ordained. He was mentioned in the letter from Cardinal Gantin on July 1 but not in the letter from Pope John Paul II on July 2. Early life Antônio de Castro Mayer was born in Campinas, São Paulo, to João Mayer, a Bavarian stonemason, and his wife, Francisca de Castro, a Brazilian peasant. One of twelve children, Antônio helped his mother support their family after João died in 1910. At age 12, he entered São Paulo's minor seminary, then run by the Premonstratensian Fathers. He entered the major seminary in 1922 and then studied at the Pontifical Gregorian University in Rome, obtaining his doctorate in theology in 1928. He was ordained to the priesthood by Cardinal Basilio Pompili on 30 October 1927. He taught philosophy, history of philosophy, and dogmatic theology at the seminary in São Paulo for the next 13 years. He became Assistant General of the São Paulo's Catholic Action in 1940 and a canon of the cathedral chapter with the title of First Treasurer in 1941. He became vicar general of the archdiocese in 1942. He was made a parish priest and the prefect of studies at the Pontifical Catholic University of São Paulo in 1945, while retaining the chairs of Religion and Catholic Social Doctrine at the Pontifical Catholic University of São Paulo. Bishop On 6 March 1948, de Castro was appointed Coadjutor Bishop of Campos and titular bishop of Priene by Pope Pius XII. He received his episcopal consecration on 23 May from Archbishop Carlo Chiarlo, Apostolic Nuncio to Brazil, with Bishop Ernesto de Paula and Archbishop Geraldo de Proença Sigaud, S.V.D., as co-consecrators. He became bishop of Campos upon the death of Bishop Octaviano de Albuquerque on 3 January 1949. He was very active in opposing liberation theology and communist infiltration of the Church and of his diocese. In 1968, the Catholic conservative group Tradition, Family and Property organized a campaign to collect signatures denouncing