Louis William Valentine DuBourg SS (French: Louis-Guillaume-Valentin DuBourg; 10 January 1766 – 12 December 1833) was a French Catholic prelate and Sulpician missionary to the United States. He built up the church in the vast new Louisiana Territory as the Bishop of Louisiana and the Two Floridas and later became the Bishop of Montauban and Archbishop of Besançon in France.