Prominent merchant, captain, and religious leader in 19th century rural Massachusetts.

Marsh was the richest and most powerful citizen of Innsmouth, Massachusetts for many years, partly because of his skill in business and partly because he traded rubber and glass trinkets for gold in the Polynesian islands. By 1838, the Polynesian natives he traded with had died, and Marsh's supply of gold dried up. This plunged the entire town of Innsmouth into an economic depression.

At this point, Marsh founded a religion based on stories he had heard from the Polynesian natives, preaching that if the citizens followed the undersea gods worshipped by the islanders in the Pacific, they would become rich and fishing would be plentiful. Marsh's Esoteric Order of Dagon grew so popular that all the other churches in town closed, either because of lack of members or because of the Order's strongarm tactics. After a plague killed half of the town's population in 1846, Marsh made himself Innsmouth's leader and only well-off citizen. Marsh died in 1878, but his family and his church ruled the town until the government, fearing the cult's influence, raided (and essentially destroyed) the town in 1927-28.

"The Shadow over Innsmouth" by H.P. Lovecraft
Encyclopedia Cthulhiana by Daniel Harms, pp. 130-131