Donald J. Sanborn (born 1957) is an American Catholic bishop, who was initially made a priest while belonging to the Society of St. Pius X under Archbishop Marcel Lefebvre in the 1970s. Sanborn was born in New York to a family of English ancestry who have relatively deep roots in the area, having arrived in New England as far back as 1632. In 1977, he was appointed the Rector of the first SSPX's seminary in the Americas at Michigan, but moved it to a larger base St. Thomas Aquinas Seminary at Connecticut two years later. As the SSPX was making gestures to the modernist Vatican, in 1983 nine American priests split from them as the Society of St. Pius V, upholding sedevacantism: Sanborn was one of the founding priests.
During the early 1990s, Sanborn turned his hand to writing and produced articles exposing the heresies of the Second Vatican Council and the reigning Anti-Pope Karol Wojtyla ("John Paul II"). He founded a scholarly quarterly journal for Catholic priests called Sacerdotium and a periodical for the laity called Catholic Restoration. Encouraged by other priests, in 1995 he founded the Most Holy Trinity Seminary for the formation of priests, originally based at Warren, Michigan but would later move to Brooksville, Florida. Sanborn has a considerable knowledge of Thomistic theology, Catholic dogma and moral teachings, as well being a polyglot with a working knowledge of English, Latin, French, Italian, Greek, German and Spanish. He was made a Catholic Bishop in 2002 by Bishop Robert McKenna, a Dominican. Sanborn has a considerable internet presence.