Port Clyde is the southernmost settlement on the St. George Peninsula in Central/coastal Maine and part of the town of St. George in Knox County, Maine, United States. In the 19th century, Port Clyde became a busy port featuring Granite quarries, tide mills for sawing timber, and shipbuilding and fish canning businesses. By the 20th century, the area attracted artists and writers. The Country of the Pointed Firs was written by Sarah Orne Jewett in St. George.
Port Clyde's Harbor was originally known as Herring Gut. Marshall Point – site of the Marshall Point Lighthouse– is Port Clyde's southernmost extremity. This lighthouse is the one to which Tom Hanks ran in the 1994 film Forrest Gump.