Marblehead is a coastal New England town in Essex County, Massachusetts, along the North Shore. Its population was 20,441 at the 2020 census. The town lies on a small peninsula that extends into the northern part of Massachusetts Bay. Attached to the town is a near island, known as Marblehead Neck, connected to the mainland by a narrow isthmus. Marblehead Harbor, protected by shallow shoals and rocks from the open sea, lies between the mainland and the Neck.