Dagoth was an ancient demon and thrall of Shuma-Gorath. He made his home in the city of Kalumesh until it sunk beneath the Atlantic Ocean off the coast of Cornwall, England. Dagoth arose in modern times to threaten the Cornish village of Penmallow, only to be banished to another plane by Doctor Strange.
Like many of Dr. Strange's foes at that time, Dagoth was a homage to the creations of H.P. Lovecraft; specifically, Dagon.