Essex is a coastal town in Essex County, Massachusetts, 26 miles (42 km) north of Boston and 13 miles (21 km) southeast of Newburyport. It is known for its former role as a center of shipbuilding. The population was 3,675 at the 2020 census.

The central village areas of Essex and South Essex make up the census-designated place of Essex.

Essex was incorporated as a town in 1819. It was previously a part of the town of Ipswich and was then called Chebacco Parish. The first European settlers arrived in 1634. At that time, the land formed part of an area inhabited by Native Americans of the Agawam tribe. The name Chebacco is Agawam in origin and refers to a large lake whose waters extend into neighboring Hamilton. Conomo Point, the easternmost part of the town, is named for the Sagamore or Chief of the Agawams, Masconomo, the leader of the tribe in the late 17th century. Early on, Chebacco Parish lobbied for status as an independent town, asking for permission to build a meeting house. In colonial times, the existence of a meeting house in a settlement conferred de facto autonomy, so Chebacco Parish was denied permission to build such a structure. Popular history tells that one written dictate was issued stating that “no man shall raise a meeting house”, so the residents of the settlement interpreted it as to mean that women would be allowed to do so. It is reported that a local woman, Madam Varney, assembled the town’s women and construction of a meeting house was carried out by them while the men looked on. Jeremiah Shepard was a minister at the church in Chebacco Parish from 1678 to 1680. He was succeeded by John Wise, who was pastor of Chebacco Parish from 1680 to his death in 1725.

According to the United States Census Bureau, the town has a total area of 15.9 square miles (41.3 km), of which 14.0 square miles (36.2 km²) is land and 2.0 square miles (5.1 km), or 12.41%, is water. The town does not have any direct access to Ipswich Bay and the Atlantic Ocean, with Essex Bay providing access through the northeast corner of town (the eastern half of the bay lies within Ipswich and Gloucester, with all of the outlet nominally belonging to Gloucester). The central part of Essex lies on marsh land that surrounds the Essex River. Essex River feeds Essex Bay, along with Castle Neck River (which provides most of the town’s border with Ipswich) and several creeks, including Walker Creek, Hardys Creek and Soginese Creek. The land that makes up the limits of the town is close to sea level, with a few low hills dotting the landscape. Chebacco Lake and the surrounding wetlands make up most of the southwestern part of the town. Essex’s population has increased at a sustainable rate over the last quarter century, so it still maintains a certain rural quality with abundant forested areas, wetlands and open spaces. There are several protected areas within town, including the Allyn-Cox Reservation, a portion of Crane Wildlife Refuge, the Stavros Reservation and the state Wildlife Management Area. The Crane Wildlife Refuge covers several of the islands in Essex Bay, including Choate Island.

Essex is bordered by Hamilton to the west, Manchester-by-the-Sea to the south, Gloucester to the east, and Ipswich to the north. Essex is located 11 miles (18 km) northeast of Salem and 33 miles (53 km) northeast of Boston. Though not accessible directly by a major highway, Route 128 clips the corner of town, with exits located in neighboring Manchester-by-the-Sea and Gloucester. Route 133 passes from northwest to southeast through town, and the eastern end of Route 22 is at Route 133 in the center of town. The Ipswich Essex Explorer bus provides weekend service during the summer connecting with the MBTA Commuter Rail at Ipswich along the Newburyport/Rockport Line, as well as providing service to Crane Beach and other nearby attractions. The Rockport portion of the commuter rail line passes through neighboring Manchester-by-the-Sea and Gloucester.

As of the census of 2000, there were 3,267 people, 1,313 households, and 887 families residing in the town. The population density was 230.7 inhabitants per square mile (89.1/km). There were 1,446 housing units at an average density of 39.4 persons/km² (102.1 persons/sq mi). The racial makeup of the town was 98.50% White, 0.15% African American, 0.12% Native American, 0.43% Asian, 0.03% Pacific Islander, 0.21% from other races, and 0.55% from two or more races. Hispanic or Latino of any race were 0.92% of the population.

There were 1,313 households, out of which 31.5% had children under the age of 18 living with them, 56.1% were married couples living together, 7.8% have a woman whose husband does not live with her, and 32.4% were non-families. 26.7% of all households were made up of individuals, and 9.4% had someone living alone who was 65 years of age or older. The average household size was 2.49 and the average family size was 3.03.