William J. Morgan was an English lay theologian and a Traditionalist Catholic apologist promoting the Sedevacantist position. His son, Father Paul Morgan, had become a priest in the Fraternal Society of Saint Pius X, which opposes Sedevacantism. Morgan was opposed to the Cassiciacum Thesis, a similar position to the Sedevacantist position, and is credited with naming that other position, sedeprivationism. He lived in the 20th century.
Morgan presided over a small lay organization, the Counter-Reformation Association, La Guerche, Monks Kirby, near Rugby, England.