Fan Casting Barnabas Marsh in H.P. Lovecraft's The Shadow Over Innsmouth

Obed Marsh was a sea captain from Innsmouth. He learned from the inhabitants of a Polynesian island a ritual to summon the Deep Ones. This was done on Devil's Reef then entering into a pact with them, offering human sacrifices in exchange for a constant supply of fish and occasionally golden artifacts. Marsh at some point founded the Esoteric Order of Dagon. He died in 1878 and his family continued their control of Innsmouth. He is the great-great-grandfather of Robert Olmstead.