Captain Obed Marsh (1800 - 1878) is the posthumous antagonist of The Shadow Over Innsmouth, a short story by H.P. Lovecraft. He was a sea captain from Innsmouth who ultimately became leader of Innsmouth and established the Esoteric Order of Dagon to worship blasphemous deities in return for wealth. He was portrayed by Alfredo Villa in Dagon, the 2001 adaptation of the book.
Captain Obed was a merchant from the isolated seafront town of Innsmouth. When Innsmouth fell on hard times, he travelled to the South Sea Islands, where he discovered a tribe named the Kanakys, who he noticed were unusually prosperous, with all the fish they could catch and a strange amount of gold items such as religious headdresses, most of which had images of strange creatures carved into them. Obed began trading with them for their gold, eventually getting the secret of the Kanakys from their chief Walakea: They had been sacrificing people to the Deep Ones, arcane fish creatures living under the sea, in return for good fishing and gold. They had also been breeding with the Deep Ones in order to fulfil the ritual and create near-immortal hybrids between humans and Deep Ones who would one day rise and overthrow humanity with an army of Shoggoths. Walakea subsequently taught Obed ancient rites relating to the Deep Ones, and Obed made a habit of returning to the island to continue trading for the gold, against his crew's protests.
In about 1838, Obed returned to the island, but discovered the Kanakys had been wiped out by a rival tribe after said tribe discovered the human sacrifice ritual. Knowing that Innsmouth's situation would worsen without the gold, he began to rail against the people of Innsmouth for worshipping the Christian God, telling them about the Deep Ones. Although the people of Innsmouth were reluctant to participate in pagan human sacrifice rituals, Obed managed to convince them to do it by appealing to the desperateness of their situation. Obed's first mate Matt Eliot, who knew exactly what the Deep Ones were and what the ritual entailed, attempted to rally the people against Obed with assistance from the Church, but Obed convinced the people to run the Christian preachers out of town and begin worship of Father Dagon and Mother Hydra, the gods of the Deep Ones, leading strange rituals at the nearby Devil's Reef which ultimately lead to the Obed leading the people of Innsmouth to kidnap and sacrifice children from neighbouring towns. Soon after, Innsmouth began to prosper, and Obed formed the Esoteric Order of Dagon to further worship the Deep Ones, buying the local Masonic Lodge as the headquarters of the Esoteric Order. Matt Eliot, who was a freemason, continued to oppose Obed, but Obed simply sacrificed him to the Deep Ones.
In 1846, the authorities finally caught wind of Obed's crimes after a large number of disappearances were reported around Innsmouth, and ambushed Obed as he was returning from Devil's Reef after a sacrifice, arresting him and 36 other members of the Esoteric Order and imprisoning them in Innsmouth Gaol. However, the Deep Ones, not wanting to lose the worship of the Esoteric Order, attacked Innsmouth and slaughtered many residents before freeing Obed and the rest of the Esoteric Order. After this, Obed forced all the residents of Innsmouth to take the Oath of Dagon. He then announced that he was going to make changes to Innsmouth, and began forcing people to mate with the Deep Ones, usually against their will. Obed himself took a Deep One as a wife in 1848, spawning an extensive family. He died in 1878.
Although Obed died many years before the story takes place, his impact upon the story is large, as thanks to his forced breeding the entire population of Innsmouth would go on to sire a population of Deep Ones who inhabited the town. Obed himself sired a Deep One family who included the story's protagonist Robert Olmstead.