Fr. Joaquín Sáenz y Arriaga, S.J. (born Joaquín Sáenz Arriaga on October 12, 1899 - died April 28, 1976) was a Mexican Jesuit and Catholic theologian. He entered the Society of Jesus in 1916 in Barcelona, Spain and left it in 1952 in Mexico, at fifty three. Because of his continuous attacks against the Second Vatican Council and the post-conciliar popes he was declared excommunicated in 1972 by the Roman Catholic bishops' conference of Mexico. He is known for being the spiritual father of sedevacantism.